MYSQL数据表操作语句

1.查看某数据库中的表

SHOW [FULL] TABLES [FROM db_name] [LIKE 'pattern']

SHOW TABLES列举了给定数据库中的非TEMPORARY表。也可以使用mysqlshow db_name命令得到此清单。

本命令也列举数据库中的其它视图。支持FULL修改符，这样SHOW FULL TABLES就可以显示第二个输出列。对于一个表，第二列的值为BASE TABLE；对于一个视图，第二列的值为VIEW。

2.查看数据表的详细信息

SHOW TABLE STATUS [FROM db_name] [LIKE 'pattern']

3.查看建表语句

SHOW CREATE TABLE tbl_name

4.建表语句

CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
    (create_definition,...) 
    [table_options]
    [partition_options]

CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
    [(create_definition,...)]
    [table_options]
    [partition_options]
    [IGNORE | REPLACE]
    [AS] query_expression

CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
    { LIKE old_tbl_name | (LIKE old_tbl_name) }

建表语句内容比较多，先来一张图看看整体结构。

在创建表格时，您可以使用TEMPORARY关键词。只有在当前连接情况下，TEMPORARY表才是可见的。当连接关闭时，TEMPORARY表被自动取消。这意味着两个不同的连接可以使用相同的临时表名称，同时两个临时表不会互相冲突，也不与原有的同名的非临时表冲突。（原有的表被隐藏，直到临时表被取消时为止。）您必须拥有CREATE TEMPORARY TABLES权限，才能创建临时表。

create_definition:
    --列名 列定义
    col_name column_definition 
    --主键约束（主键索引）
  | [CONSTRAINT [symbol]] PRIMARY KEY [index_type] (index_col_name,...)
      [index_option] ...
  | {INDEX|KEY} [index_name] [index_type] (index_col_name,...)
      [index_option] ...
   --唯一约束 
  | [CONSTRAINT [symbol]] UNIQUE [INDEX|KEY]
      [index_name] [index_type] (index_col_name,...)
      [index_option] ...
  | {FULLTEXT|SPATIAL} [INDEX|KEY] [index_name] (index_col_name,...)
      [index_option] ...
   --外键约束 
  | [CONSTRAINT [symbol]] FOREIGN KEY
      [index_name] (index_col_name,...) reference_definition
  --自定义检查约束  
  | CHECK (expr)

列定义

column_definition:
    data_type [NOT NULL | NULL] [DEFAULT default_value]
      [AUTO_INCREMENT] [UNIQUE [KEY] | [PRIMARY] KEY]
      [COMMENT 'string']
      [COLUMN_FORMAT {FIXED|DYNAMIC|DEFAULT}]
      [STORAGE {DISK|MEMORY|DEFAULT}]
      [reference_definition]
  | data_type [GENERATED ALWAYS] AS (expression)
      [VIRTUAL | STORED] [UNIQUE [KEY]] [COMMENT comment]
      [NOT NULL | NULL] [[PRIMARY] KEY]

1）一个整数列可以拥有一个附加属性AUTO_INCREMENT。当您向一个已编入索引的AUTO_INCREMENT列中插入一个NULL值（建议）或0时，此列被设置为下一个序列的值。通常情况下为value+1，此处value是当前在表中的列的最大值。AUTO_INCREMENT序列从1开始。为了让MySQL与部分ODBC应用软件相兼容，您可以使用以下查询方法找到最后一个插入行的AUTO_INCREMENT值：SELECT * FROM tbl_name WHERE auto_col IS NULL。

2）DEFAULT子句用于为列指定一个默认值。默认值必须为一个常数，不能为一个函数或一个表达式，有一种情况例外。例如，一个日期列的默认值不能被设置为一个函数，如NOW()或CURRENT_DATE。不过，有一种例外，您可以对TIMESTAMP列指定CURRENT_TIMESTAMP为默认值。BLOB和TEXT列不能被赋予默认值。

3）对于列的评注可以使用COMMENT选项来进行指定。评注通过SHOW CREATE TABLE和SHOW FULL COLUMNS语句显示。

4）在UNIQUE索引中，所有的值必须互不相同。

5）PRIMARY KEY是一个唯一KEY，一个表只有一个PRIMARY KEY。PRIMARY KEY可以是一个多列索引。但是，在列规约中使用PRIMARY KEY关键字属性无法创建多列索引。这么做只能把一个列标记为主列。您必须使用一个单独的PRIMARY KEY（index_col_name, ...）子句。

实数据类型

data_type:
    BIT[(length)]
  | TINYINT[(length)] [UNSIGNED] [ZEROFILL]
  | SMALLINT[(length)] [UNSIGNED] [ZEROFILL]
  | MEDIUMINT[(length)] [UNSIGNED] [ZEROFILL]
  | INT[(length)] [UNSIGNED] [ZEROFILL]
  | INTEGER[(length)] [UNSIGNED] [ZEROFILL]
  | BIGINT[(length)] [UNSIGNED] [ZEROFILL]
  | REAL[(length,decimals)] [UNSIGNED] [ZEROFILL]
  | DOUBLE[(length,decimals)] [UNSIGNED] [ZEROFILL]
  | FLOAT[(length,decimals)] [UNSIGNED] [ZEROFILL]
  | DECIMAL[(length[,decimals])] [UNSIGNED] [ZEROFILL]
  | NUMERIC[(length[,decimals])] [UNSIGNED] [ZEROFILL]
  | DATE
  | TIME[(fsp)]
  | TIMESTAMP[(fsp)]
  | DATETIME[(fsp)]
  | YEAR
  | CHAR[(length)] [BINARY]
      [CHARACTER SET charset_name] [COLLATE collation_name]
  | VARCHAR(length) [BINARY]
      [CHARACTER SET charset_name] [COLLATE collation_name]
  | BINARY[(length)]
  | VARBINARY(length)
  | TINYBLOB
  | BLOB
  | MEDIUMBLOB
  | LONGBLOB
  | TINYTEXT [BINARY]
      [CHARACTER SET charset_name] [COLLATE collation_name]
  | TEXT [BINARY]
      [CHARACTER SET charset_name] [COLLATE collation_name]
  | MEDIUMTEXT [BINARY]
      [CHARACTER SET charset_name] [COLLATE collation_name]
  | LONGTEXT [BINARY]
      [CHARACTER SET charset_name] [COLLATE collation_name]
  | ENUM(value1,value2,value3,...)
      [CHARACTER SET charset_name] [COLLATE collation_name]
  | SET(value1,value2,value3,...)
      [CHARACTER SET charset_name] [COLLATE collation_name]
  | JSON
  | spatial_type

索引与约束

index_col_name:
    col_name [(length)] [ASC | DESC]

index_type:
    USING {BTREE | HASH}

index_option:
    KEY_BLOCK_SIZE [=] value
  | index_type
  | WITH PARSER parser_name
  | COMMENT 'string'

reference_definition:
    REFERENCES tbl_name (index_col_name,...)
      [MATCH FULL | MATCH PARTIAL | MATCH SIMPLE]
      [ON DELETE reference_option]
      [ON UPDATE reference_option]

reference_option:
    RESTRICT | CASCADE | SET NULL | NO ACTION

 表基本属性设置

table_options:
    table_option [[,] table_option] ...

table_option:
    ENGINE [=] engine_name
  | AUTO_INCREMENT [=] value
  | AVG_ROW_LENGTH [=] value
  | [DEFAULT] CHARACTER SET [=] charset_name
  | CHECKSUM [=] {0 | 1}
  | [DEFAULT] COLLATE [=] collation_name
  | COMMENT [=] 'string'
  | COMPRESSION [=] {'ZLIB'|'LZ4'|'NONE'}
  | CONNECTION [=] 'connect_string'
  | DATA DIRECTORY [=] 'absolute path to directory'
  | DELAY_KEY_WRITE [=] {0 | 1}
  | ENCRYPTION [=] {'Y' | 'N'}
  | INDEX DIRECTORY [=] 'absolute path to directory'
  | INSERT_METHOD [=] { NO | FIRST | LAST }
  | KEY_BLOCK_SIZE [=] value
  | MAX_ROWS [=] value
  | MIN_ROWS [=] value
  | PACK_KEYS [=] {0 | 1 | DEFAULT}
  | PASSWORD [=] 'string'
  | ROW_FORMAT [=] {DEFAULT|DYNAMIC|FIXED|COMPRESSED|REDUNDANT|COMPACT}
  | STATS_AUTO_RECALC [=] {DEFAULT|0|1}
  | STATS_PERSISTENT [=] {DEFAULT|0|1}
  | STATS_SAMPLE_PAGES [=] value
  | TABLESPACE tablespace_name
  | UNION [=] (tbl_name[,tbl_name]...)

表分区：

partition_options:
    PARTITION BY
        { [LINEAR] HASH(expr)
        | [LINEAR] KEY [ALGORITHM={1|2}] (column_list)
        | RANGE{(expr) | COLUMNS(column_list)}
        | LIST{(expr) | COLUMNS(column_list)} }
    [PARTITIONS num]
    [SUBPARTITION BY
        { [LINEAR] HASH(expr)
        | [LINEAR] KEY [ALGORITHM={1|2}] (column_list) }
      [SUBPARTITIONS num]
    ]
    [(partition_definition [, partition_definition] ...)]

partition_definition:
    PARTITION partition_name
        [VALUES
            {LESS THAN {(expr | value_list) | MAXVALUE}
            |
            IN (value_list)}]
        [[STORAGE] ENGINE [=] engine_name]
        [COMMENT [=] 'comment_text' ]
        [DATA DIRECTORY [=] 'data_dir']
        [INDEX DIRECTORY [=] 'index_dir']
        [MAX_ROWS [=] max_number_of_rows]
        [MIN_ROWS [=] min_number_of_rows]
        [TABLESPACE [=] tablespace_name]
        [(subpartition_definition [, subpartition_definition] ...)]

subpartition_definition:
    SUBPARTITION logical_name
        [[STORAGE] ENGINE [=] engine_name]
        [COMMENT [=] 'comment_text' ]
        [DATA DIRECTORY [=] 'data_dir']
        [INDEX DIRECTORY [=] 'index_dir']
        [MAX_ROWS [=] max_number_of_rows]
        [MIN_ROWS [=] min_number_of_rows]
        [TABLESPACE [=] tablespace_name]

依据某个查询建立新表：

query_expression:
    SELECT ...   (Some valid select or union statement)

对建表举例：

CREATE TABLE `students` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `stu_num` varchar(30) NOT NULL,
  `stu_name` varchar(30) NOT NULL,
  `sex` enum('M','F') DEFAULT 'M',
  `major` varchar(50) DEFAULT NULL,
  `grade` tinyint(4) DEFAULT NULL,
  --主键
  PRIMARY KEY (`id`),
  --唯一约束
  UNIQUE KEY `stu_num` (`stu_num`)
)
--指定存储引擎和字符集
ENGINE=InnoDB DEFAULT CHARSET=utf8;

依据某个查询建立新表：

CREATE TABLE students_clone SELECT * FROM students;

按照此方式建立的students_clone表表结构将与students一致，且数据一致。

CREATE TABLE students_clone_1 LIKE students;

按照此方式建立的students_clone表表结构将与students一致，新建的数据表为空。

5.删除数据表

DROP [TEMPORARY] TABLE [IF EXISTS] tbl_name [, tbl_name]

DROP TABLE用于取消一个或多个表。您必须有每个表的DROP权限。所有的表数据和表定义会被取消，所以使用本语句要小心。

6.清空表数据

TRUNCATE [TABLE] tbl_name

TRUNCATE TABLE用于完全清空一个表。