方便后面拼接 条件 使用AND 时报错
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举个例子
SELECT * FROM STSCORE WHERE 1=1 ${IF(LEN(CLASSNO_)==0,""," AND CLASSNO='"+CLASSNO+"'")}${IF(LEN(STUDENTNO_)==0,""," AND STUDENTNO='"+STUDENTNO_+"'")}
如果不用 1=1
则判断起来麻烦
SELECT * FROM STSCORE WHERE${IF(LEN(CLASSNO_)==0,""," CLASSNO='"+CLASSNO+"'")}${IF(LEN(STUDENTNO_)==0,"",IF(LEN(CLASSNO_)==0," STUDENTNO='"+STUDENTNO_+"'""," AND STUDENTNO='"+STUDENTNO_+"'")}