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Download Informix Guide to SQL: Syntax, Version 6.0
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Identifier Using CURRENT, DATETIME, INTERVAL, and NULL in INSERT You cannot use the CURRENT, DATETIME, INTERVAL, or NULL keyword as the name of a procedure with the INSERT statement. For example, if you define a variable called null, when you try to insert the value null into a column, you receive a syntax error. This is shown in the following example: CREATE PROCEDURE problem() . . . DEFINE null INT; LET null = 3; INSERT INTO tab VALUES (null); -- error, inserts NULL, not 3 Using NULL and SELECT in a Condition If you define a variable with the name null or select, using it in a condition that uses the IN keyword is ambiguous. The following example shows three conditions that cause problems: in an IF statement, in a WHERE clause of a SELECT statement, and in a WHILE condition: CREATE PROCEDURE problem() . . . DEFINE x,y,select, null, INT; DEFINE pfname CHAR[15]; LET x = 3; LET select = 300; LET null = 1; IF x IN (select, 10, 12) THEN LET y = 1; -- problem if IF x IN (1, 2, 4) THEN SELECT customer_num, fname INTO y, pfname FROM customer WHERE customer IN (select , 301 , 302, 303); -- problem in WHILE x IN (null, 2) -- problem while . . . END WHILE; 1-480 Syntax
