mysql如何查询所有表和字段信息

SELECT
 *
FROM
 information_schema.`TABLES`
WHERE
 TABLE_SCHEMA = 'erp';

SELECT
 TABLE_NAME,
 TABLE_COMMENT
FROM
 information_schema.`TABLES`
WHERE
 TABLE_SCHEMA = 'erp';

SELECT
 TABLE_SCHEMA AS '库名',
 TABLE_NAME AS '表名',
 COLUMN_NAME AS '列名',
 ORDINAL_POSITION AS '列的排列顺序',
 COLUMN_DEFAULT AS '默认值',
 IS_NULLABLE AS '是否为空',
 DATA_TYPE AS '数据类型',
 CHARACTER_MAXIMUM_LENGTH AS '字符最大长度',
 NUMERIC_PRECISION AS '数值精度(最大位数)',
 NUMERIC_SCALE AS '小数精度',
 COLUMN_TYPE AS 列类型,
 COLUMN_KEY 'KEY',
 EXTRA AS '额外说明',
 COLUMN_COMMENT AS '注释'
FROM
 information_schema.`COLUMNS`
WHERE
 TABLE_SCHEMA = 'erp'
ORDER BY
 TABLE_NAME,
 ORDINAL_POSITION;

SELECT
 C.TABLE_SCHEMA AS '库名',
 T.TABLE_NAME AS '表名',
 T.TABLE_COMMENT AS '表注释',
 C.COLUMN_NAME AS '列名',
 C.COLUMN_COMMENT AS '列注释',
 C.ORDINAL_POSITION AS '列的排列顺序',
 C.COLUMN_DEFAULT AS '默认值',
 C.IS_NULLABLE AS '是否为空',
 C.DATA_TYPE AS '数据类型',
 C.CHARACTER_MAXIMUM_LENGTH AS '字符最大长度',
 C.NUMERIC_PRECISION AS '数值精度(最大位数)',
 C.NUMERIC_SCALE AS '小数精度',
 C.COLUMN_TYPE AS 列类型,
 C.COLUMN_KEY 'KEY',
 C.EXTRA AS '额外说明'
FROM
 information_schema.`TABLES` T
LEFT JOIN information_schema.`COLUMNS` C ON T.TABLE_NAME = C.TABLE_NAME
AND T.TABLE_SCHEMA = C.TABLE_SCHEMA
WHERE
 T.TABLE_SCHEMA = 'erp' 
ORDER BY
 C.TABLE_NAME,
 C.ORDINAL_POSITION;