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Variable Declaration - SQL
SQL's support for variables is very similar to Tutorial D's, except that the syntax for creating persistent variables-base tables-is quite different from that used to declare local variables. Example is SQL's counterpart of that example in the theory book but, as you know, CREATE TABLE is used for base tables.
Example: A Variable Declaration
DECLARE SN SID DEFAULT SID ('S1');
DECLARE in place of VAR and DEFAULT in place of INIT. The effect is exactly the same apart from the fact that, as already noted, SQL's type SID (here assumed to be a distinct type). The key word DEFAULT is perhaps a strange choice as that word normally suggests action to be taken by the system when no specific action is explicitly demanded by the user. Here it is used to state explicitly an immediate assignment to the variable being declared.
Bulk Binds advantages In the Embedded Oracle RDBMS, the PL/SQL engines accept any valid PL/SQL subprogram or block. As the figure shows, the PL/SQL engine executes all procedur
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Count Operator in SQL Example: Counting the students who have scored more than 50 in some exam (SELECT COUNT (*) FROM (SELECT DISTINCT StudentId FROM EXAM_MARK WHE
Parameter and Keyword Description: table_reference: This keyword identifies the table or view that should be accessible when you execute the UPDATE statement, and for wh
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Transactions in SQL BEGIN TRANSACTION, COMMIT, and ROLLBACK, SQL has the same syntax except for START in place of BEGIN. However, START TRANSACTION is used only for outermost
Example of Check Constraints Example: Workaround for when subqueries not permitted in CHECK constraints CREATE FUNCTION NO_MORE_THAN_20000_ENROLMENTS ( ) RETURNS BOOLEAN
Procedures The procedure is a subprogram which can take parameters and be invoked. Normally, you can use a procedure to perform an action. The procedure has 2 sections: the spe
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