if語(yǔ)句

IF 語(yǔ)句

IF (value1,value2,value3) value1 為布爾表達(dá)式或bu布爾值 value2 當(dāng)value1結(jié)果為true時(shí)返回的結(jié)果 value3 當(dāng)value1結(jié)果為false時(shí)返回的結(jié)果

例1:

SELECT IF(2=1,'對(duì)','錯(cuò)')AS status; 結(jié)果為:對(duì) SELECT IF(2!=1,'對(duì)','錯(cuò)')AS status; 結(jié)果為:錯(cuò)

例1測(cè)試結(jié)果:

mysql> SELECT IF(2=1,'對(duì)','錯(cuò)')AS status; +--------+ | status | +--------+ | 錯(cuò) | +--------+ 1 row in set

mysql> SELECT IF(2!=1,'對(duì)','錯(cuò)')AS status; +--------+ | status | +--------+ | 對(duì) | +--------+ 1 row in set

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例2:

SELECT IF(true,'對(duì)','錯(cuò)')AS status; 結(jié)果為: 對(duì) SELECT IF(false,'對(duì)','錯(cuò)')AS status; 結(jié)果為: 錯(cuò)

例2測(cè)試結(jié)果:

mysql> SELECT IF(true,'對(duì)','錯(cuò)')AS status; +--------+ | status | +--------+ | 對(duì) | +--------+ 1 row in set

mysql> SELECT IF(false,'對(duì)','錯(cuò)')AS status; +--------+ | status | +--------+ | 錯(cuò) | +--------+ 1 row in set

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