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exist方法sql语句优化 

本地没有mssql和oracle，所以没法测试，但是，mysql 使用select 1 from TABLENAME where CONDITION limit 1可能更好
This commit is contained in:
linbaozhong 2021-12-01 12:13:26 +08:00
parent 885f582677
commit 46ed0688f6
1 changed files with 2 additions and 2 deletions
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4
internal/statements/query.go
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@ -392,7 +392,7 @@ func (statement *Statement) GenExistSQL(bean ...interface{}) (string, []interfac
} else if statement.dialect.URI().DBType == schemas.ORACLE { } else if statement.dialect.URI().DBType == schemas.ORACLE {
sqlStr = fmt.Sprintf("SELECT * FROM %s WHERE (%s) %s AND ROWNUM=1", tableName, joinStr, condSQL) sqlStr = fmt.Sprintf("SELECT * FROM %s WHERE (%s) %s AND ROWNUM=1", tableName, joinStr, condSQL)
} else { } else {
sqlStr = fmt.Sprintf("SELECT * FROM %s %s WHERE %s LIMIT 1", tableName, joinStr, condSQL) sqlStr = fmt.Sprintf("SELECT 1 FROM %s %s WHERE %s LIMIT 1", tableName, joinStr, condSQL)
} }
args = condArgs args = condArgs
} else { } else {
@ -401,7 +401,7 @@ func (statement *Statement) GenExistSQL(bean ...interface{}) (string, []interfac
} else if statement.dialect.URI().DBType == schemas.ORACLE { } else if statement.dialect.URI().DBType == schemas.ORACLE {
sqlStr = fmt.Sprintf("SELECT * FROM %s %s WHERE ROWNUM=1", tableName, joinStr) sqlStr = fmt.Sprintf("SELECT * FROM %s %s WHERE ROWNUM=1", tableName, joinStr)
} else { } else {
sqlStr = fmt.Sprintf("SELECT * FROM %s %s LIMIT 1", tableName, joinStr) sqlStr = fmt.Sprintf("SELECT 1 FROM %s %s LIMIT 1", tableName, joinStr)
} }
args = []interface{}{} args = []interface{}{}
} }