Oracle PL/SQL:CREATE TABLE statement: create a table with primary key.CREATE TABLE statement can be used to create table objects in database. It is possible to add constraints like primary key ,foreign key while table creation.Primary key is the unique identifier for a row of data.One ...
默认情况下 InnoDB存储引擎有一个共享表空间 ibdata1 ,即所有数据都放在这个表空间内 。 如果我们启用了参数innodb_file_per_table ,则每张表内的数据可以单独放到一个表空间内 。段就是表,区就是连续的几个页,页是最小单位。 在数据目录中(通常是 /var/lib/mysql/ ),会看到它包含有: *.frm文件:保存了...
Here, the SQL command checks if a table namedCompaniesexists, and if not, it creates a table with specified columns. Create Table Using Another Existing Table In SQL, we can create a new table by duplicating an existing table's structure. Let's look at an example. -- create a backup t...
Create Table Foreign Key Syntax Like the primary key definition, you can declare a foreign key both inline and out of line in the SQL Create Table command. Inline foreign keys are declared like this: CREATEtable_name(column_name data_typeREFERENCESother_table_name(other_column_name),...); ...
一、查看外键:show create table 表名; 二、删除外键:alter table 表名 drop foreign key 外键名; 三、外键的级联操作 1、 on delete cascade:表示主表中的数据被删除后,从表中相关数据也会被删除 2、 on update cascade:表示主表中的数九被修改后,从表中的相关数据也会被修改 ...
1>.查看CREATE TABLE的帮助信息 mysql>?CREATETABLEName:'CREATE TABLE'Description: Syntax: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][...
= column_set_name XML COLUMN_SET FOR ALL_SPARSE_COLUMNS <table_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } [ CLUSTERED | NONCLUSTERED ] ( column_name [ ASC | DESC ] [ ,... n ] ) [ WITH FILLFACTOR = fillfactor | WITH ( <index_option> [ ,... ...
syntaxsql 复制 -- Create a new table. CREATE TABLE { database_name.schema_name.table_name | schema_name.table_name | table_name } ( { column_name <data_type> [ <column_options> ] } [ ,...n ] ) [ WITH ( <table_option> [ ,...n ] ) ] [;] <column_options> ::= [ ...
] referenced_table_name [ ( ref_column ) ] | CHECK ( logical_expression ) } <table_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } { NONCLUSTERED ( column_name [ ASC | DESC ] [ ,... n ]) | NONCLUSTERED HASH ( column_name [ ,... n ] ) WITH ...
= column_set_name XML COLUMN_SET FOR ALL_SPARSE_COLUMNS <table_constraint> ::= [ CONSTRAINT constraint_name ] { { PRIMARY KEY | UNIQUE } [ CLUSTERED | NONCLUSTERED ] ( column_name [ ASC | DESC ] [ ,... n ] ) [ WITH FILLFACTOR = fillfactor | WITH ( <index_option> [ ,... ...