My SQL with 003 data table base operation syntax

Data Sheet

1. View Data Sheet
2. Modify Table Name
3. Modify field names
4. modifying field data types
5. Add Delete-field
6. Constraint (primary foreign key default check)

To view the table structure:

• Syntax: Desribe (description) table_name;

　　　　　　DESC table_name;

• Syntax: show CREATE TABLE table_name;

Show CREATE TABLE table_name \g;

Modify Table Name:

• Syntax: ALTER TABLE table_name rename to table_new;

Modify Field Name:

• Syntax: ALTER TABLE table_name change table_filed table_newfiled new_type;

modifying field data types

To modify the field data type:

• Grammar : ALTER TABLE table_name modify Field_table New_type (ten);

Add Delete-field:

• Syntax: ALTER TABLE table_name add new_table_name new_type;
• Syntax: ALTER TABLE TABLE_NAME DROP TABLE_NAME;

Constraints:

PRIMARY KEY constraint	FOREIGN KEY constraints	CHECK constraints	Default Constraints
PrimaryKey	Foreigkey	Check	Default

PRIMARY KEY constraint:

• Syntax: ALTER TABLE users ADD constraint pk_users_users_qq PRIMARY KEY (USERS_QQ);

FOREIGN KEY constraints:

• Syntax: ALTER TABLE scoers ADD constraint fk_scoers_users_qq FOREIGN KEY (USERS_QQFK) REFERENCES users (UESRS_QQ);

CHECK constraints:

• Syntax:ALTER table table_name add constraint ck_ (games) Table name _ (scoers) field CHECK (scoers>0);

Default value:

• Syntax: Alter TABLE TABLE_NAME alter user_sex SET DEFAULT ' male ';

2017-07-02

My SQL with 003 data table base operation syntax