1. case when

• 簡單判斷

CASE [col_name] 
WHEN [value1] THEN [result1]
WHEN [value1] THEN [result2]
....
ELSE [default] 
END [new_col_name]

• 表達(dá)式判斷

CASE 
WHEN [expr] THEN [result1]
WHEN [expr] THEN [result2]
....
ELSE [default] 
END [new_col_name]

2. 將tableB得數(shù)據(jù)批量添加到tableA

INSERT INTO [table_A] (col1, col2 ...)
SELECT (col1, col2 ...) FROM [table_B] WHERE [condition]

3. 生成不帶橫桿[-]并且不重復(fù)得uuid

SELECT REPLACE (MD5(uuid()), '-', '')

4. 批量更新

UPDATE [table_name] SET [col_name] = [value] WHERE [condition]

或者

UPDATE [table_A] SET [col_name] = (SELECT [col_name] FROM [table_B] WHERE [condition])

5. 新增列

ALTER TABLE [table_name] ADD [new_col_name] [data_type] COMMENT [comment]

6. 修改列名

ALTER TABLE [table_name] CHANGE [old_col_name] [new_col_name] [data_type] COMMENT [comment]

7. 修改列得數(shù)據(jù)類型

ALTER TABLE [table_name] MODIFY COLUMN [col_name] [data_type] DEFAULT NULL;

8. 新建一張表A順便從表B把數(shù)據(jù)拷過來（A和B結(jié)構(gòu)相同）

CREATE TABLE [table_A] SELECT * FROM [table_B]

9.批量更新不重復(fù)的uuid

UPDATE [table_name] SET [id_column_name] = (SELECT MD5(FLOOR(RAND() * 999999)))