fix: 修复statement GenExistSQL 只有表名，没有RefTable时，未拼接别名Alias的BUG

internal/statements/query.go

@@ -314,8 +314,6 @@ func (statement *Statement) GenExistSQL(bean ...interface{}) (string, []interfac
 		return statement.Limit(1).GenGetSQL(b)
 	}
 
-	tableName = statement.quote(tableName)
-
 	buf := builder.NewWriter()
 	if statement.dialect.URI().DBType == schemas.MSSQL {
 		if _, err := fmt.Fprintf(buf, "SELECT TOP 1 *"); err != nil {