MySQL III: Table operations

Read Catalogue

• Introduction to a storage engine
• Two table Introduction
• Three Create a table
• Four view table structure
• Five data types
• Six-table integrity constraints
• Seven Modified tables ALTER TABLE
• Eight copy table
• Nine Delete a table

Introduction to a storage engine

The storage engine is a table type, and MySQL has different processing mechanisms depending on the table type

See: http://www.cnblogs.com/llhtjwq/p/8306708.html

Two table Introduction

Table is equivalent to a file, a record in the table is equivalent to a row of the file, but a record in the table has a corresponding title, called the table field

Id,name,qq,age is called a field, the rest, a row of content is called a record

Three Create a table

# Syntax: CREATE TABLE table name (field name 1 type [(width) constraint], field name 2 Type [(width) constraint], field name 3 Type [(width) constraint]); # Note:1. In the same table, field names cannot be the same as 2. Width and constraints optional 3. Field names and types are required

View Codeinserting data into a table

Note Note: Do not add commas to the last field in the table

Four view table structure

 MariaDB [db1]> describe T1; #   +-------+-----------------------+------+-----+---------+-- -----+| Field | Type | Null | Key | Default | Extra |+-------+-----------------------+------+-----+---------+-------+| ID | Int (11) |     YES | |       NULL | || name | varchar (50) |     YES | |       NULL | || sex | Enum ( " male  , "  female   ") |     YES | |       NULL | || Age | Int (3) |     YES | |       NULL | |+-------+-----------------------+------+-----+---------+-------+  MariaDB [DB1]  > Show CREATE TABLE T1\g; #   
 

Five data types

Http://www.cnblogs.com/llhtjwq/p/8306716.html

Six-table integrity constraints

Http://www.cnblogs.com/llhtjwq/p/8306721.html

Seven Modified tables ALTER TABLE

syntax:1. Modify the table name alter the table name RENAME a                           new table name; 2. Add field      ALTER table name                          add field name  data type [integrity constraint ...],                          add field name  data type [integrity constraint ...];      ALTER Table name                          ADD field name  data type [integrity constraint ...]  First;     ALTER Table Table name                          ADD field name  data type [integrity constraint ...]  After field name;                             3. Delete field      ALTER table name                           drop field name; 4. Modify field      ALTER TABLE name                           MODIFY  field name data type [integrity constraint ...];      ALTER Table table name change                           old field name new field name old data type [integrity constraint condition ...];      ALTER table name change                           old field name new data type [integrity constraint ...];

Example

Eight copy table

Copy table structure + record (key does not replicate: primary key, foreign key, and index) MySQL  from Service; Copy table structure only MySQL  from service where 1=2;        condition is false, no record is found for empty set (0.00 sec) MySQL from service where 1=2;  Query OK, 0 rows affected (0.00 sec) records:0  duplicates:0  warnings:0mysql> CREATE TABLE t 4 like employees;

Nine Delete a table

DROP table name;

MySQL III: Table operations