MySQL存儲過程錯誤IF ... THEN ... END IF;聲明

Question

我有一個引發錯誤的MySQL存儲過程。

DELIMITER $$ 

DROP PROCEDURE IF EXISTS `test_schema`.`TEST_SPROC` $$ 
CREATE PROCEDURE `test_schema`.`TEST_SPROC` (IN var0 INT, var1 INT) 
BEGIN 

    DECLARE var0 INT; 
    DECLARE var1 INT; 

    SELECT COUNT(*) INTO var0 FROM INFORMATION_SCHEMA.`TABLES` 
    WHERE `TABLE_SCHEMA`='test_schema' AND `TABLE_NAME`='original_table'; 

    SELECT COUNT(*) INTO var1 FROM INFORMATION_SCHEMA.`COLUMNS` 
    WHERE `TABLE_SCHEMA`='test_schema' AND `TABLE_NAME`='new_table' 
    AND `COLUMN_NAME`='id'; 

    IF var0=1 THEN 
    RENAME TABLE test_schema.original_table TO test_schema.new_table; 
    END IF; 

    IF var1=1 THEN 
    ALTER TABLE test_schema.new_table CHANGE id AccountID VARCHAR; 

    END IF;  #error is thrown here. 

END $$ 

DELIMITER ; 

錯誤：

Script line: 4 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '; END IF;

END' at line 15

什麼是錯我的if語句？

Answer 1

改變這一行：

ALTER TABLE test_schema.new_table CHANGE id AccountID VARCHAR; 

這樣：

ALTER TABLE test_schema.new_table CHANGE id AccountID VARCHAR(100); 

當然，你應該指定VARCHAR列，它是適當的長度。我剛剛以VARCHAR(100)爲例。

Answer 2

您必須指定alter table語句的長度。請參閱下面的註釋：

IF varTable=1 THEN 
    RENAME TABLE test_schema.original_table TO test_schema.new_table; 
    SELECT COUNT(*) INTO varColumn FROM INFORMATION_SCHEMA.`COLUMNS` 
    WHERE `TABLE_SCHEMA`='test_schema' AND `TABLE_NAME`='new_table' 
    AND `COLUMN_NAME`='id'; 

    IF varColumn=1 THEN 
     #The following statement must be "VARCHAR(255)" not just "VARCHAR" 
     ALTER TABLE test_schema.new_table CHANGE id AccountID VARCHAR(255); 
    ELSE 
     #statements. 
    END IF; 
END IF;