The maximum number of components in the DECODE function, including expr, searches, results, and default, is 255. If expr is null, then Oracle returns the result of the first search that is also null. In a DECODE function, Oracle considers two nulls to be equivalent. If the first result has the datatype CHAR or if the first result is null, then Oracle converts the return value to the datatype VARCHAR2. It is possible to use DECODE, but you'd have to use nested DECODEs and you'd end up with something that's much harder to. select 1 value1, case when 'a' 'a' and 'b' 'b' then 'pass' else 'fail' end result from dual VALUE1 RESULT - 1 pass. Syntax: DECODE ( expression, search, result, search, result. The simplest answer is don't use decode, use a case statement instead, e.g. The DECODE function is supported in the various versions of the Oracle/PLSQL, including, Oracle 12c, Oracle 11g, Oracle 10g and Oracle 9i. It is used to work as an IF-THEN-ELSE statement. Oracle automatically converts the return value to the same datatype as the first result. DECODE is an advanced function that the Oracle database supports. Oracle automatically converts expr and each search value to the datatype of the first search value before comparing. DECODEORACLE is a synonym for the Oracle mode version of the DECODE function, and is available in all modes. Consequently, Oracle never evaluates a search if a previous search is equal to expr. That is, the database evaluates each search value only before comparing it to expr, rather than evaluating all search values before comparing any of them with expr. Oracle Database uses short-circuit evaluation. The search, result, and default values can be derived from expressions. SELECT 1 'cast (null)' FROM dual WHERE SYSDATE < DECODE (1,0,cast (null as date),SYSDATE) That will return a row regardless of the session's nlsdateformat because the decode will now return a date data type and you're comparing a date to a date. If the first search-result pair are numeric, then Oracle compares all search-result expressions and the first expr to determine the argument with the highest numeric precedence, implicitly converts the remaining arguments to that datatype, and returns that datatype. In a DECODE function, Oracle considers two nulls to be equivalent. Alternately, you can have the decode return the correct data type by doing an explicit cast. The string returned is of VARCHAR2 datatype and is in the same character set as the first result parameter. expr, search, and result can be any of the datatypes CHAR, VARCHAR2, NCHAR, or NVARCHAR2. If expr and search are character data, then Oracle compares them using nonpadded comparison semantics. The arguments can be any of the numeric types ( NUMBER, BINARY_FLOAT, or BINARY_DOUBLE) or character types. We know that COL1 in the test table contains null in all rows except the first. If the first parameter is any value other than null, it is returned unchanged. If the value in the first parameter is null, the function returns the value in the second parameter. If default is omitted, then Oracle returns null. The NVL function allows you to replace null values with a default value. If no match is found, then Oracle returns default. If expr is equal to a search, then Oracle Database returns the corresponding result. Examplesįrom MariaDB 10.3.Description of the illustration decode.gifĭECODE compares expr to each search value one by one. The DECODE function can be used in Oracle/PLSQL. If no matches are found, the default expression is returned, or NULL if no default is provided.ĭECODE_ORACLE is a synonym for the Oracle-mode version of the function, and is available in all modes. If it finds a match, the corresponding result expression is returned. In Oracle mode from MariaDB 10.3.2, DECODE compares expr to the search expressions, in order. The resulting string will be the original string only if pass_str is the same. The syntax for DECODE function is DECODE( expression, search, result, search, result. We hope that this EDUCBA information on SQL DECODE() was beneficial to you. It is a built-in function in ORACLE / PL SQL database management servers. The function is a close relative of CASE statements. crypt_str should be a string returned from ENCODE(). DECODE function is used to perform procedural IF-THEN-ELSE logic in SQL. In the default mode, DECODE decrypts the encrypted string crypt_str using pass_str as the In a DECODE function, Oracle considers two nulls to be equivalent. In all modes from MariaDB 10.3.2: DECODE_ORACLE(expr, search_expr, result_expr ) In Oracle mode from MariaDB 10.3.2: DECODE(expr, search_expr, result_expr )
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |