SET
SET in SQL is a statement used to modify the values of a variable, which is already defined in the database, or to modify the global system variables. This can be used in the preparation of the environment or to adjust the behavior of the database system.
Example
SET @name = 'John Doe';SELECT @name;Output
+-----------+| @name |+-----------+| John Doe |+-----------+Explanation
The SET command in the SQL statement is used to assign a value to the variable @name. The SELECT command is then executed to display the value of the @name variable, which in this case is ‘John Doe’.
Example
SET timezone TO 'America/New_York';SHOW timezone;Output
TimeZone--------------------------- America/New_YorkExplanation
The SET statement is used to change the current setting of a run-time configuration option for the duration of the current session. The example above is changing the timezone to ‘America/New_York’. The SHOW command is displaying the current set timezone.
Example
DECLARE @TestVariable INT;SET @TestVariable = 5;SELECT @TestVariable;Output
5Explanation
The variable @TestVariable is declared to be of type INT. Subsequently, the SET statement assigns the value 5 to @TestVariable. The SELECT statement then retrieves the value, outputting 5.
Example
SET SERVEROUTPUT ONDECLARE test_variable NUMBER(2);BEGIN test_variable := 15; dbms_output.put_line('The value of test_variable is ' || test_variable);END;/Output
The value of test_variable is 15Explanation
In the example code, the SERVEROUTPUT feature of SQL*PLUS is enabled with the SET SERVEROUTPUT ON command. This allows the DBMS_OUTPUT.PUT_LINE to function. Within a PL/SQL block, a variable named test_variable of NUMBER type is declared and set to 15. The dbms_output.put_line command prints the appended string and the value of test_variable which gives us our output.