1、查詢MySQL庫下所有表名，資料為空的表

SELECT
    table_name,
    table_rows
FROM
    information_schema. TABLES
WHERE
    table_schema = 'ahbo'
AND table_rows < 1;

2、查詢指定庫擁有某欄位的表

SELECT DISTINCT
    TABLE_NAME
FROM
    information_schema. COLUMNS
WHERE
    COLUMN_NAME = 'columnName'
AND TABLE_SCHEMA = 'dbName
 
'
AND TABLE_NAME NOT LIKE 'vw%';

3、修改指定資料庫中所有varchar型別的表字段的字符集為UTF8，並將排序規則修改為utf8_general_ci

SELECT CONCAT('ALTER TABLE `', table_name, '` MODIFY `', column_name, '` ', DATA_TYPE, '(', CHARACTER_MAXIMUM_LENGTH, ') CHARACTER SET UTF8 COLLATE utf8_general_ci', (CASE WHEN IS_NULLABLE = 'NO' THEN ' NOT NULL
 
' ELSE '' END), ';')
別名
FROM information_schema.COLUMNS
WHERE TABLE_SCHEMA = 'SchoolUserOnline_20170416'
AND DATA_TYPE = 'varchar'
AND
(
    CHARACTER_SET_NAME != 'utf8'
    OR
    COLLATION_NAME != 'utf8_general_ci'
);

4、修改指定資料庫中所有資料表的字符集為UTF8，並將排序規則修改為utf8_general_ci

SELECT CONCAT('ALTER TABLE ', table_name, '
 
 CONVERT TO CHARACTER SET  utf8 COLLATE utf8_unicode_ci;')
FROM information_schema.TABLES
WHERE TABLE_SCHEMA = 'databaseName'