For more information about Oracle (NYSE:ORCL), visit. Oracle offers a comprehensive and fully integrated stack of cloud applications and platform services. My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts. To view full details, sign in with your My Oracle Support account.ĭon't have a My Oracle Support account? Click to get started! This document will show how to use the SIGN function to achieve the same result. DECODE is proprietary to Oracle.Ĩ) CASE executes faster in the Optimizer than does DECODE.ĩ) CASE is a statement while DECODE is a function.How to Create Expression Using Decode and Greater Than > or Less Than ) and less than ( < ) operator is NOT supported in an expression. DECODE: Decode is an function in sql.Its a way of. SELECT CASE WHEN NULL is NULL THEN 'This is Null'ħ) CASE complies with ANSI SQL. While working on one of the projects got a chance to explore DECODE and CASE STATEMENT in Oracle Database. SELECT CASE NULL WHEN NULL THEN 'This is Null' ORA-00932: inconsistent datatypes: expected NUMBER got CHARĦ) CASE handles NULL differently : SELECT DECODE(NULL,NULL,'This is Null' The DECODE function can be used in Oracle/PLSQL. exec proc_test(decode(:a,'THREE',3,0)) ĥ) CASE expects datatype consistency, DECODE does not. exec proc_test(case :a when 'THREE' then 3 else 0 end) Ībove statement will not give error but below statement gives error. If the ELSE is not coded, NULL is returned.ĬASE can even work as a parameter to a procedure call, while DECODE cannot. If none of the WHEN values match the given expression, the ELSE value is returned. The first TRUE expression cause oracle to return the corresponding THEN value. PLSQL stands for 'Procedural Language extensions to SQL', and is an extension of SQL that is used in Oracle.PLSQL is closely integrated into the SQL language, yet it adds programming constructs that are not native to SQL. The searched CASE allow multiple comparison expression (, =, BETWEEN, LIKE, IN, IS NULL, etc.). Oracle is a relational database technology developed by Oracle. If you omit fmt, then date is converted to a VARCHAR2 value as follows. If the ELSE is not coded, NULL is returned. TOCHAR (datetime) converts a datetime or interval value of DATE, TIMESTAMP, TIMESTAMP WITH TIME ZONE, TIMESTAMP WITH LOCAL TIME ZONE, INTERVAL DAY TO SECOND, or INTERVAL YEAR TO MONTH data type to a value of VARCHAR2 data type in the format specified by the date format fmt. The DECODE function in Oracle allows you to have IF-THEN-ELSE logic in your SQL statements. If none of the WHEN value match with given value/expression, the ELSE values is returned. It cant change other values, such as 0, or advanced logic compared to CASE and DECODE. SQL> SELECT id, DECODE(col1, NULL, 'ZERO', col1) AS output FROM nulltesttab ORDER BY id ID OUTPUT - 1 ONE 2 ZERO 3 ZERO 4 ZERO 4 rows selected. Simple case expression use for an equal condition on the given value or expression.The first WHEN value which is match with given value, return corresponding THEN value. The DECODE function is not specifically for handling null values, but it can be used in a similar way to the NVL function, as shown by the following example. It is used to work as an IF-THEN-ELSE statement. Syntax The syntax for the DECODE function in Oracle/PLSQL is: DECODE. Let’s see the following example: SELECT DECODE ( 1, 1, 'Equal' ) Code language: SQL (Structured Query Language) (sql) In this example, the DECODE () function compares the first argument (one) with the second argument (also one). A) Simple CASE statement: CASE expression WHEN this1 THEN that1 DECODE is an advanced function that the Oracle database supports. The Oracle PL/SQL ROUND function is a built-in function that is used to round. The SQL DECODE () function allows you to add procedure if-then-else logic to queries. The CASE expression is a more flexible version of the DECODE function. Oracle support two flavors of CASE, simple and searched. The CASE expression was first added to SQL in Oracle8i. Oracle9i extends its support to PL/SQL to allow CASE to be used as an expression or statement.
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