查数据库表和字段

查指定数据库表的字段和描述 ===================================================
SELECT 
    COLUMN_NAME AS '字段名',
    COLUMN_COMMENT AS '字段注释',
    COLUMN_TYPE AS '数据类型',
    IS_NULLABLE AS '是否可为空'
FROM 
    INFORMATION_SCHEMA.COLUMNS 
WHERE 
    TABLE_SCHEMA = 'joinleader_app_run' 
    AND TABLE_NAME = 'hj_huohao_gmci2am7'
ORDER BY 
    ORDINAL_POSITION;

查询所有数据库中的表清单 ===================================================
SELECT 
    table_schema AS '数据库名',
    table_name AS '表名',
    table_comment AS '表注释'
FROM 
    information_schema.tables
WHERE 
    table_schema NOT IN ('information_schema', 'mysql', 'performance_schema', 'sys')
ORDER BY 
    table_schema, table_name;

查询所有数据库中的字段及注释 ===================================================
SELECT 
    t.table_schema AS '数据库名',
    t.table_name AS '表名',
    c.column_name AS '字段名',
    c.column_type AS '字段类型',
    c.column_comment AS '字段注释'
FROM 
    information_schema.tables t
JOIN 
    information_schema.columns c ON t.table_schema = c.table_schema AND t.table_name = c.table_name
WHERE 
    t.table_schema NOT IN ('information_schema', 'mysql', 'performance_schema', 'sys')
ORDER BY 
    t.table_schema, t.table_name, c.ordinal_position;