1. substr()
syntax:
SUBSTR (string, start_position, [length_of_substring])
eg:
substr('This is a test', 6, 2) would return 'is'
remarks:
- The original string is assumed to start at position one (1).
- If substring_length is omitted, then Oracle returns all characters to the end of char.
- If substring_length is less than 1, then Oracle returns null.
2. instr()
syntax:
instr(string,substring,[position],[occurrence])
eg:
select instr('corporate floor','or',3,2) from dual; would return '14'
remarks:
- The default values of both position and occurrence are 1, meaning Oracle begins searching at the first character of string for the first occurrence of substring.
- The return value is relative to the beginning of string, regardless of the value of position.
我的用例:
CASE UPPER(T1.COLUMN_TYPE)
WHEN SUBSTR(RF1.PARAM_VALUE,1,INSTR(RF1.PARAM_VALUE,'~')-1) THEN SUBSTR(RF1.PARAM_VALUE,INSTR(RF1.PARAM_VALUE,'~')+1)
ELSE T1.PRODUCT_TYPE_DESC
END AS PRODUCT_TYPE
COLUMN_TYPE: AN APPLE
PARAM_VALUE: AN APPLE~FRUIT
SUBSTR(RF1.PARAM_VALUE,1,INSTR(RF1.PARAM_VALUE,’~’)-1): AN APPLE
INSTR(RF1.PARAM_VALUE,’~’)+1: 10
这里用于字段参数化,从一个参数表的某个相应字段中对比取值,对比~前的值,如果一致,那么取~后的值。