Exam Dump Oracle
Which two are true about unused columns? (Choose two.) A. A query can return data from unused columns, but no DML is possible on those columns. B. Unused columns retain their data until they are dropped. C. Once a column has been set to unused, a new column with the same name can be added to the table. D. The DESCRIBE command displays unused columns. E. A primary key column cannot be set to unused. F. A foreign key column cannot be set to unused.
B , C Why: Option B: "Unused columns retain their data until they are dropped." This is correct. Unused columns keep their data until they are explicitly removed from the table. Setting a column to unused does not immediately delete its data; it only marks the column as unavailable. Option C: "Once a column has been set to unused, a new column with the same name can be added to the table." This is correct. Once a column is marked as unused, you can add a new column with the same name to the table, because the unused column is effectively 'removed' from the table's structure in a logical sense.
Which two clauses are required for this command to execute successfully? (Choose two.) A. the access driver TYPE clause B. the DEFAULT DIRECTORY clause C. the REJECT LIMIT clause D. the LOCATION clause E. the ACCESS PARAMETERS clause
B , D
Which two statements are true about Oracle synonyms? (Choose two.) A. Any user can create a PUBLIC synonym. B. A synonym has an object number. C. All private synonym names must be unique in the database. D. A synonym can be created on an object in a package. E. A synonym can have a synonym.
B , E Why: A. Any user can create a PUBLIC synonym.( x) Must have Create Publc Syn Priv. B. A synonym has an object number. C. All private synonym names must be unique in the database. (X) Unique in the schema. D. A synonym can be created on an object in a package. (X) A schema object can't be in a package E. A synonym can have a synonym.
See Image: How many rows will be displayed? A. 64 B. 6 C. 3 D. 12
B - 6
Examine this query: What is the result? A. an error B. no rows C. 1 row D. 3 rows E. 6 rows F. 8 rows
B : Because that Where clause is NEVER valid.
Which two statements are true about conditional INSERT ALL? (Choose two.) A. Each row returned by the subquery can be inserted into only a single target table. B. A single WHEN condition can be used for multiple INTO clauses. C. Each WHEN condition is tested for each row returned by the subquery. D. It cannot have an ELSE clause. E. The total number of rows inserted is always equal to the number of rows returned by the subquery.
B, C
Which three statements are true about Structured Query Language (SQL)? (Choose three.) A. It requires that data be contained in hierarchical data storage. B. It best supports relational databases. C. It provides independence for logical data structures being manipulated from the underlying physical data storage. D. It is the only language that can be used for both relational and object-oriented databases. E. It guarantees atomicity, consistency, isolation, and durability (ACID) features. F. It is used to define encapsulation and polymorphism for a relational table.
B, C , E
Which three statements are true about Oracle synonyms? (Choose three.) A. A synonym cannot be created for a PL/SQL package. B. A synonym can be available to all users. C. A SEQUENCE can have a synonym. D. Any user can drop a PUBLIC synonym. E. A synonym created by one user can refer to an object belonging to another user.
B, C, E A synonym is like an alias for any kind of database object! It could be a procedure, sequence, PL/SQL package, table, view, etc. Synonyms can be made public by specifying PUBLIC in the CREATE command CREATE PUBLIC SYNONYM emp FOR hr.employees;
Examine the description of the PRODUCTS table: Which three queries use valid expressions? (Choose three.) A. SELECT product_id, unit_price, S "Discount", unit_price + surcharge - discount FROM products; B. SELECT product_id, (unit_price * 0.15 / (4.75 + 552.25)) FROM products; C. SELECT product_id, (expiry_date - delivery_date) * 2 FROM products; D. SELECT product_id, unit_price || 5 "Discount", unit_price + surcharge - discount FROM products; E. SELECT product_id, expiry_date * 2 FROM products; F. SELECT product_id, unit_price, unit_price + surcharge FROM products;
B, C, F
Which three queries execute successfully? (Choose three.) A. SELECT 1 - SYSDATE - DATE '2019-01-01' FROM DUAL; B. SELECT SYSDATE - DATE '2019-01-01' - 1 FROM DUAL; C. SELECT SYSDATE / DATE '2019-01-01' - 1 FROM DUAL; D. SELECT SYSDATE - 1 - DATE '2019-01-01' FROM DUAL; E. SELECT (SYSDATE - DATE '2019-01-01') / 1 FROM DUAL; F. SELECT 1 / SYSDATE - DATE '2019-01-01' FROM DUAL;
B, D, E
Which three statements are true about single-row functions? (Choose three.) A. They return a single result row per table. B. They can be nested to any level. C. They can accept only one argument. D. The argument can be a column name, variable, literal or an expression. E. They can be used only in the WHERE clause of a SELECT statement. F. The data type returned can be different from the data type of the argument.
B, D, F
Examine the partial query: SELECT city, last_name AS lname FROM members ...;You want to display all cities that contain the string AN. The cities must be returned in ascending order, with the last names further sorted in descending order. Which two clauses must you add to the query? (Choose two.) A. ORDER BY 1, 2 B. ORDER BY 1, lname DESC C. WHERE city IN ('%AN%') D. WHERE city = '%AN%' E. WHERE city LIKE '%AN%' F. ORDER BY last_name DESC, city ASC
B, E
The SALES table has columns PROD_ID and QUANTITY_SOLD of data type NUMBER.Which two queries execute successfully? (Choose two.) A. SELECT prod_id FROM sales WHERE quantity_sold > 55000 AND COUNT(*) > 10 GROUP BY COUNT(*) > 10; B. SELECT prod_id FROM sales WHERE quantity_sold > 55000 GROUP BY prod_id HAVING COUNT(*) > 10; C. SELECT COUNT(prod_id) FROM sales GROUP BY prod_id WHERE quantity_sold > 55000; D. SELECT prod_id FROM sales WHERE quantity_sold > 55000 AND COUNT(*) > 10 GROUP BY prod_id HAVING COUNT(*) > 10; E. SELECT COUNT(prod_id) FROM sales WHERE quantity_sold > 55000 GROUP BY prod_id;
B, E You cannot have a COUNT() in a WHERE clause. That is what the HAVING clause is for
Which three statements are true about Structured Query Language (SQL)? (Choose three.) A. It requires that data be contained in hierarchical data storage. B. It best supports relational databases. C. It provides independence for logical data structures being manipulated from the underlying physical data storage. D. It is the only language that can be used for both relational and object-oriented databases. E. It guarantees atomicity, consistency, isolation, and durability (ACID) features. F. It is used to define encapsulation and polymorphism for a relational table.
B,C,E
Example of Deferred Contraint
-- Begin a transaction BEGIN; -- Insert into departments INSERT INTO departments (department_id, department_name) VALUES (1, 'Sales'); -- Temporarily insert into employees with a department_id that does not yet exist INSERT INTO employees (employee_id, employee_name, department_id) VALUES (101, 'John Doe', 1); -- Correct the department_id in employees by adding it to the departments table INSERT INTO departments (department_id, department_name) VALUES (2, 'Marketing'); -- Commit the transaction COMMIT;
You own table DEPARTMENTS, referenced by views, indexes, and synonyms.Examine this command which executes successfully: DROP TABLE departments PURGE; Which three statements are true? (Choose three.) A. It will remove the DEPARTMENTS table from the database. B. It will drop all indexes on the DEPARTMENTS table. C. It will remove all views that are based on the DEPARTMENTS table. D. It will remove all synonyms for the DEPARTMENTS table. E. Neither can it be rolled back nor can the DEPARTMENTS table be recovered. F. It will delete all rows from the DEPARTMENTS table, but retain the empty table.
A, B, E
Which two statements are true about the COUNT function? (Choose two.) A. COUNT(*) returns the number of rows in a table including duplicate rows and rows containing NULLs in any column. B. It can only be used for NUMBER data types. C. COUNT(DISTINCT inv_amt) returns the number of rows excluding rows containing duplicates and NULLs in the INV_AMT column. D. COUNT(inv_amt) returns the number of rows in a table including rows with NULL in the INV_AMT column E. A SELECT statement using the COUNT function with a DISTINCT keyword cannot have a WHERE clause.
A, C Why: Group functions do not consider NULL values, except the COUNT(*)
Which two statements are true about *_TABLES views? (Choose two.) A. USER_TABLES displays all tables owned by the current user. B. You must have ANY TABLE system privileges, or be granted object privileges on the table, to view a table in USER_TABLES. C. All users can query DBA_TABLES successfully. D. You must have ANY TABLE system privileges, or be granted object privileges on the table, to view a table in DBA_TABLES. E. ALL_TABLES displays all tables owned by the current user. F. You must have ANY TABLE system privileges, or be granted object privileges on the table, to view a table in ALL_TABLES.
A, D
Which two are true? (Choose two.) A. All existing rows in the ORDERS table are updated. B. The subquery is executed before the UPDATE statement is executed. C. The subquery is not a correlated subquery. D. The subquery is executed for every updated row in the ORDERS table. E. The UPDATE statement executes successfully even if the subquery selects multiple rows.
A, D A is correct because, if where statement does not match, the customer_name is set to NULL
Which two statements are true after execution? (Choose two.) A. The primary key constraint will be enabled and IMMEDIATE. B. The foreign key constraint will be enabled and DEFERRED. C. The primary key constraint will be enabled and DEFERRED. D. The foreign key constraint will be disabled. E. The foreign key constraint will be enabled and IMMEDIATE.
A, D Not E because only the Primary Key Contraint is being directly enabled in the alter table statement.
Which two statements are true about TRUNCATE and DELETE? (Choose two.) A. DELETE can use a WHERE clause to determine which row(s) should be removed. B. TRUNCATE can use a WHERE clause to determine which row(s) should be removed. C. TRUNCATE leaves any indexes on the table in an UNUSABLE state. D. The result of a TRUNCATE can be undone by issuing a ROLLBACK. E. The result of a DELETE can be undone by issuing a ROLLBACK.
A, E
Which two are true? (Choose two.) A. ADD_MONTHS adds a number of calendar months to a date. B. CEIL requires an argument which is a numeric data type. C. CEIL returns the largest integer less than or equal to a specified number. D. LAST_DAY returns the date of the last day of the current month only. E. LAST_DAY returns the date of the last day of the month for the date argument passed to the function. F. LAST_DAY returns the date of the last day of the previous month only.
A, E Remember CEIL returns the SMALLEST integer greater than or equal to the provided value Last_Day will just return the date of the last day of the month for the date provided.
Which three are true about scalar subquery expressions? (Choose three.) A. They can be nested. B. They cannot be used in the VALUES clause of an INSERT statement. C. A scalar subquery expression that returns zero rows evaluates to zero. D. They can be used as default values for columns in a CREATE TABLE statement. E. A scalar subquery expression that returns zero rows evaluates to NULL. F. They cannot be used in GROUP BY clauses.
A, E , F
Which two methods should you use to prevent prompting for a hire date value when this query is executed? (Choose two.) A. Use the DEFINE command before executing the query. B. Replace '&1' with '&&1' in the query. C. Use the UNDEFINE command before executing the query. D. Execute the SET VERIFY OFF command before executing the query. E. Execute the SET VERIFY ON command before executing the query. F. Store the query in a script and pass the substitution value to the script when executing it.
A, F
Which two are true? (Choose two.) A. CONCAT joins two character strings together. B. CONCAT joins two or more character strings together. C. FLOOR returns the largest positive integer less than or equal to a specified number. D. INSTR finds the offset within a character string, starting from position 0. E. INSTR finds the offset within a string of a single character only. F. FLOOR returns the largest integer less than or equal to a specified number.
A, F Concat only can do 2 character items at a time. FLOOR is the opposite of CEIL. it rounds down to the LARGEST Integer that is less than or equal to the provided number.
See image
C
You need to allow user ANDREW to: 1. Modify the TITLE and ADDRESS columns of your CUSTOMERS table. 2. GRANT that permission to other users.Which statement will do this? Which statement will do this? A. GRANT UPDATE ON customers.title, customers.address TO andrew; B. GRANT UPDATE (title, address) ON customers TO andrew; C. GRANT UPDATE (title, address) ON customers TO andrew WITH GRANT OPTION; D. GRANT UPDATE ON customers.title, customers.address TO andrew WITH ADMIN OPTION; E. GRANT UPDATE ON customers.title, customers.address TO andrew WITH GRANT OPTION; F. GRANT UPDATE (title, address) ON customers TO andrew WITH ADMIN OPTION;
C
Which is true about the ROUND, TRUNC and MOD functions? A. TRUNC(MOD(25,3),-1) is invalid. B. ROUND(MOD(25,3),-1) is invalid. C. ROUND(MOD(25,3),-1) and TRUNC(MOD(25,3),-1) are both valid and give the same result. D. ROUND(MOD(25,3),-1) and TRUNC(MOD(25,3),-1) are both valid but give different results.
C The remainder of 25/3 is 1. 25/3 = 8 > 8 x 3 = 24 > 25-24 = Remainder 1
The EMPLOYEES table contains columns EMP_ID of data type NUMBER and HIRE_DATE of data type DATE. You want to display the date of the first Monday after the completion of six months since hiring. The NLS_TERRITORY parameter is set to AMERICA in the session and, therefore, Sunday is the first day of the week. Which query can be used? A. SELECT emp_id, ADD_MONTHS(hire_date, 6), NEXT_DAY('MONDAY') FROM employees; B. SELECT emp_id, NEXT_DAY(ADD_MONTHS(hire_date, 6), 1) FROM employees; C. SELECT emp_id, NEXT_DAY(MONTHS_BETWEEN(hire_date, SYSDATE), 6) FROM employees; D. SELECT emp_id, NEXT_DAY(ADD_MONTHS(hire_date, 6), 'MONDAY') FROM employees;
D
Which two statements are true about the SET VERIFY ON command? (Choose two.) A. It displays values for variables used only in the WHERE clause of a query. B. It displays values for variables created by the DEFINE command. C. It can be used only in SQL*Plus. D. It displays values for variables prefixed with &&. E. It can be used in SQL Developer and SQL*Plus.
D, E
Examine this list of requirements for a sequence: 1. Name: EMP_SEQ 2. First value returned: 1 3. Duplicates are never permitted. 4. Provide values to be inserted into the EMPLOYEES.EMPLOYEE_ID column. 5. Reduce the chances of gaps in the values. Which two statements will satisfy these requirements? (Choose two.) A. CREATE SEQUENCE emp_seq START WITH 1 INCREMENT BY 1 CYCLE; B. CREATE SEQUENCE emp_seq START WITH 1 INCREMENT BY 1 CACHE; C. CREATE SEQUENCE emp_seq; D. CREATE SEQUENCE emp_seq START WITH 1 INCREMENT BY 1 NOCACHE; E. CREATE SEQUENCE emp_seq NOCACHE; F. CREATE SEQUENCE emp_seq START WITH 1 CACHE;
D, E NO CACHE reduces the chances of gaps in values.
Which two are true about transactions in the Oracle Database? (Choose two.) A. DML statements always start new transactions. B. DDL statements automatically commit only data dictionary updates caused by executing the DDL. C. A session can see uncommitted updates made by the same user in a different session. D. A DDL statement issued by a session with an uncommitted transaction automatically commits that transaction. E. An uncommitted transaction is automatically committed when the user exits SQL*Plus.
D, E Why: A. DML statements always start new transactions. (X). Not always B. DDL statements automatically commit only data dictionary updates caused by executing the DDL. (X) Not "only" data dictionary C. A session can see uncommitted updates made by the same user in a different session. (X) in the same session D. A DDL statement issued by a session with an uncommitted transaction automatically commits that transaction. E. An uncommitted transaction is automatically committed when the user exits SQL*Plus.
DDL. What it does and examples.
DDL (Data Definition Language): Purpose: Define and manage database structures and schema. Commands: CREATE, ALTER, DROP, TRUNCATE. Transactional: Commands often auto-commit and changes cannot always be rolled back.
DML. What it does and examples.
DML (Data Manipulation Language): Purpose: Manage and manipulate data within tables. Commands: SELECT, INSERT, UPDATE, DELETE. Transactional: Operations can be rolled back or committed.
Data Type Precedence. Order By Precedence. BINARY_FLOAT Character data types Datetime and interval data types BINARY_DOUBLE All other built-in data types NUMBER
Datetime and interval data types BINARY_DOUBLE BINARY_FLOAT NUMBER Character data types All other built-in data types
What does specifically adding the Key word CONSTRAINT do?
It allows you to name the constraint for dropping and readding later.
What does CASCADE do?
It makes sure whatever's done to the Parent table (Table with Primary Key) is done to the child table (Table with the related foreign key). So a Delete CASCADE will delete any child table rows corresponding to the parent table.
MOD function MOD(numerator, denominator)
returns the remainder of a division between two numbers
ON DELETE SET NULL Meaning?
specifies what happens to the corresponding value in the child table foreign key column when a row in the parent table primary key column is deleted.
When you issue the DELETE FROM tablename command without specifying a WHERE condition, ____. a. all rows will be deleted b. the last row will be deleted c. no rows will be deleted d. the first row will be deleted
A
What does 8 and 2 mean in data type: NUMBER(8,2)
8 is the number of whole digits in total. 2 is the number of digits allowed after a decimal point.
In your session, the NLS_DATE_FORMAT is DD-MM-YYYY. There are 86400 seconds in a day. Examine this result: DATE ------------02-JAN-2020 Which statement returns this? A. SELECT TO_CHAR(TO_DATE('29-10-2019') + INTERVAL '2' MONTH + INTERVAL '4' DAY - INTERVAL '120' SECOND, 'DD-MON-YYYY') AS "date" FROM DUAL; B. SELECT TO_CHAR(TO_DATE('29-10-2019') + INTERVAL '3' MONTH + INTERVAL '7' DAY - INTERVAL '360' SECOND, 'DD-MON-YYYY') AS "date" FROM DUAL; C. SELECT TO_CHAR(TO_DATE('29-10-2019') + INTERVAL '2' MONTH + INTERVAL '5' DAY - INTERVAL '120' SECOND, 'DD-MON-YYYY') AS "date" FROM DUAL; D. SELECT TO_CHAR(TO_DATE('29-10-2019') + INTERVAL '2' MONTH + INTERVAL '5' DAY - INTERVAL '86410' SECOND, 'DD-MON- YYYY') AS "date" FROM DUAL; E. SELECT TO_CHAR(TO_DATE('29-10-2019') + INTERVAL '2' MONTH + INTERVAL '6' DAY - INTERVAL '120' SECOND, 'DD-MON-YYYY') AS "date" FROM DUAL;
C Why: Option C is the statement that returns the result 02-JAN-2020. The statement converts the string '29-10-2019' to a date using the TO_DATE function, then adds an interval of 2 months and an interval of 5 days, and subtracts an interval of 120 seconds. The resulting date is then converted to a string using the TO_CHAR function with the format model 'DD-MON-YYYY', which produces the result 02-JAN-2020. Here is the calculation: TO_DATE('29-10-2019') = October 29, 2019 + INTERVAL '2' MONTH = December 29, 2019 + INTERVAL '5' DAY = January 3, 2020 - INTERVAL '120' SECOND = January 2, 2020 we get 03-01-2020, as of midnight, and then we subtract - INTERVAL '120' SECOND i.e. 2 minutes, hence we get answer as '02-JAN-2020'
The STORES table has a column START_DATE of data type DATE, containing the date the row was inserted.You only want to display details of rows where START_DATE is within the last 25 months.Which WHERE clause can be used? A. WHERE TO_NUMBER(start_date - SYSDATE) <= 25 B. WHERE MONTHS_BETWEEN(start_date, SYSDATE) <= 25 C. WHERE MONTHS_BETWEEN(SYSDATE, start_date) <= 25 D. WHERE ADD_MONTHS(start_date, 25) <= SYSDATE
C date1: Usually the later date date 2: Usually the earlier date
Which two are true about granting object privileges on tables, views, and sequences? (Choose two.) A. INSERT can be granted only on tables and sequences. B. DELETE can be granted on tables, views, and sequences. C. SELECT can be granted on tables, views, and sequences. D. ALTER can be granted only on tables and sequences. E. REFERENCES can be granted only on tables.
C , D Why: A. INSERT can be granted only on tables and sequences. (FALSE, table + synonym) B. DELETE can be granted on tables, views, and sequences. (FALSE, only table) C. SELECT can be granted on tables, views, and sequences. (TRUE) D. ALTER can be granted only on tables and sequences. (FALSE, ALTER is system priv. not object) E. REFERENCES can be granted only on tables. (TRUE, tables + materialised views, which are different than 'normal' views)
Which three statements are true about GLOBAL TEMPORARY TABLES? (Choose three.) A. GLOBAL TEMPORARY TABLE space allocation occurs at session start. B. GLOBAL TEMPORARY TABLE rows inserted by a session are available to any other session whose user has been granted select on the table. C. A TRUNCATE command issued in a session causes all rows in a GLOBAL TEMPORARY TABLE for the issuing session to be deleted. D. Any GLOBAL TEMPORARY TABLE rows existing at session termination will be deleted. E. A DELETE command on a GLOBAL TEMPORARY TABLE cannot be rolled back. F. A GLOBAL TEMPORARY TABLE'S definition is available to multiple sessions.
C, D, F
'&1'
Enter value for 1: Prompts user to enter a value for whatever comes after the & sign &&1 will prompt it at least once, but will store the value entered for all &&1 occurences.
What does it mean when a column is the Primary Key
Every row for that column is UNIQUE. None two rows are the same. AND NO NULL VALUES ALLOWED
Operator Precedence Order (from highest to lowest)
High to Low: Unary Operators: + (Unary plus) - (Unary minus) NOT (Logical NOT) Multiplicative Operators: * (Multiplication) / (Division) % (Modulus) Additive Operators: + (Addition) - (Subtraction) Concatenation Operator: || (String concatenation) Relational Operators: = (Equal to) != (Not equal to) < (Less than) > (Greater than) <= (Less than or equal to) >= (Greater than or equal to) BETWEEN (Range check) LIKE (Pattern matching) IN (Set membership) IS NULL (Null check) Logical Conditions AND (Logical AND) OR (Logical OR) NOT (Logical NOT) Assignment Operators: := (Assignment, in procedural SQL)
Diff between Immediate Constraint and Deferred constraint
Immediate Constraints: - Checked immediately after each SQL statement. - Default behavior in Oracle. - Ensures data integrity is enforced at each step of the transaction. Deferred Constraints: - Checked only at the end of the transaction (upon COMMIT). - Useful for complex transactions where temporary violations are necessary but overall data integrity is maintained by the end of the transaction. after you COMMIT - Must explicitly say "DEFERRABLE" and "INITIALLY DEFERRED" else it will be immediate.
Condition Precedence
NOT (Logical NOT) AND (Logical AND) OR (Logical OR)
FOREIGN KEY Constraint:
Purpose: Ensures referential integrity between tables. It links columns in one table to columns in another table. Behavior: Ensures that the value in the foreign key column must exist in the referenced primary key column of another table. Example: CREATE TABLE departments ( department_id NUMBER PRIMARY KEY, department_name VARCHAR2(50) ); CREATE TABLE employees ( employee_id NUMBER PRIMARY KEY, department_id NUMBER, FOREIGN KEY (department_id) REFERENCES departments(department_id) );
NOT NULL Constraint
Purpose: Ensures that a column cannot have null values. Behavior: Forces the column to always contain a value. Example: CREATE TABLE employees ( employee_id NUMBER PRIMARY KEY, first_name VARCHAR2(50) NOT NULL );
UNIQUE Constraint
Purpose: Ensures that all values in a column or a set of columns are unique across the table. Behavior: Allows null values but ensures that non-null values are unique. Example CREATE TABLE employees ( employee_id NUMBER PRIMARY KEY, email VARCHAR2(100) UNIQUE );
CHECK Constraint:
Purpose: Ensures that all values in a column satisfy a specific condition or set of conditions. Behavior: Allows you to enforce domain integrity by restricting the range or type of values that can be inserted. Example: CREATE TABLE employees ( employee_id NUMBER PRIMARY KEY, salary NUMBER CHECK (salary >= 0) );
DEFAULT Constraint:
Purpose: Provides a default value for a column when no value is specified during an insert operation. Behavior: Automatically inserts the default value into the column if no explicit value is provided. Example: CREATE TABLE employees ( employee_id NUMBER PRIMARY KEY, hire_date DATE DEFAULT SYSDATE );
PRIMARY KEY Constraint:
Purpose: Uniquely identifies each row in a table. Each table can have only one primary key. Behavior: Ensures that the column or set of columns defined as the primary key contains unique values and does not accept null values. Example: CREATE TABLE employees ( employee_id NUMBER PRIMARY KEY, first_name VARCHAR2(50), last_name VARCHAR2(50) );
Scalar subqueries
also known as single-value subqueries, are subqueries that return exactly one value—one row and one column. These subqueries can be used in places where a single value is expected, such as in a SELECT list, a WHERE clause, or as part of an expression. They are called "scalar" because the result is a scalar value (i.e., a single value) rather than a set of rows.
single-row functions
are functions that operate on a single row of data at a time and return a single result for each row. These functions can be used in various contexts, such as in SELECT statements, WHERE clauses, and ORDER BY clauses. They are essential for performing operations like calculations, transformations, and data formatting on individual rows of data.
Correlated subquery meaning
a subquery that refers to one or more columns in the outer query.
