alter table allow null

' VALUES (' 1 ', ' smtphost ', ' email ', ' send mail server address ', ' smtp.163.com ');INSERT into ' auc_settings ' VALUES (' 2 ', ' title ', ' email ', ' email ' headers ', ' email verification ');INSERT into ' auc_settings ' VALUES (' + ', ' smstplcode ', ' SMS ', ' ali Big Fish ' template number ', ' sms_6740890 ');INSERT into ' auc_settings ' VALUES (' + ', ' smstype ', ' SMS ', ' Ali Big Fish Message type ', ' normal ');3. How does this relationship need to be maintained if there is a f

' VALUES (' 1 ', ' smtphost ', ' email ', ' send mail server address ', ' smtp.163.com ');INSERT into ' auc_settings ' VALUES (' 2 ', ' title ', ' email ', ' email ' headers ', ' email verification ');INSERT into ' auc_settings ' VALUES (' + ', ' smstplcode ', ' SMS ', ' ali Big Fish ' template number ', ' sms_6740890 ');INSERT into ' auc_settings ' VALUES (' + ', ' smstype ', ' SMS ', ' Ali Big Fish Message type ', ' normal ');3. How does this relationship need to be maintained if there is a f

MySQL Tutorial alter modify Word Name Table name structure Add column ALTER TABLE statementThe ALTER TABLE statement is used to add, modify, or delete columns in an existing table. SQ

Mysql tutorial alter name table name structure add Column Alter table statementThe alter table statement is used to add, modify, or delete columns in an existing table. SQL

Mysql changes the table structure: add, delete, modify, and adjust the field order to add a field: altertable 'user _ movement_log 'AddcolumnGatewayIdintnotnulldefault0AFTER 'regionid' (after which field is added) Delete the field: altertable 'user _ movement_log 'dropcolumnGatewayi Mysql changes the table structure: add, delete, modify fields, adjust the field order to add fields:

the last column. Alter column specifies a new default value for the COLUMN or deletes the old default value. If the old default value is deleted and the column can be NULL, the new default value is NULL. If the column cannot be NULL, MySQL assigns a default value. The default value is described in the 7.7 create

MySQL Tutorial PHP tutorial dynamically add Column ALTER table to tableAdd the MySQL statement of the column asALTER TABLE tablename ADD COLUMN columnName varchar () NOT NULL*/Database Tutorial Connection method$db = ' 111cnNet ';$conn = mysql_pconnect (' localhost ', ' root ', ' root ') or Die (Mysql_error ());mysql_s

ALTER TABLE Parse instance: sql:1. Add columns 2. Add columns, adjust column order 3. Increase the index 4. Increase the constraint 5. Increase the full-text index FULL-TEXT6. Change the default value of the column 7. Change the column name (type, order) 8. Do not change the column name 9. Delete Column 10. Delete the primary key 11. Delete Index 12. Change the character set Create a tableCREATE

type.Tips: we can also use change to achieve the modify effect. We only need to write the same field name after it.Add fields without integrity constraints Copy codeThe Code is as follows:Mysql> alter table person add sex boolean;Query OK, 0 rows affected (0.21 sec)Records: 0 Duplicates: 0 Warnings: 0 The sex here is followed by only the data type, without the integrity constraints.Add fields with integrit

Alter table table_name enable row movement, altertable_name Row movement is literally interpreted as moving rows. by default, a row in an oracle data block does not move in its lifecycle, that is, its rowid does not change. however, in some scenarios, we want the row rowid to change. In this case, we need to start the row movement feature of the table. Use the

original varchar (25) to varchar (20) Modify Field name The Code is as follows: Mysql> alter table person change stu_name name varchar (25 ); Query OK, 0 rows affected (0.20 sec) Records: 0 Duplicates: 0 Warnings: 0 Stu_name is the original name and name is the new name. It should be noted that no matter whether the data type is changed, the subsequent data types must be written If you do not modify th

Tags: reference HTML div mys full serve data type EOF modifiedSqlALTER TABLE Statement ALTER TABLE StatementThe ALTER table statement is used to add, delete, or modify columns in an existing table.SQL ALTER

use change to achieve the modify effect. we only need to write the same field name after it. Add fields without integrity constraints Mysql> alter table person add sex boolean; Query OK, 0 rows affected (0.21 sec) Records: 0 Duplicates: 0 Warnings: 0 The sex here is followed by only the data type, without the integrity constraints. Add fields with integrity constraints Mysql>

SQL statement set of The alter TABLE in mysql, including adding, modifying, and deleting fields, renaming tables, and adding and deleting primary keys. This article introduces the SQL statement set of the alter table of the MySql database. if you are interested, learn about the SQL statement set of The

// Set the field in the existing table to auto_increment.Alter table tablename change ID int (2) not null auto_increment; // Add a field and set the primary keyAlter table tabelname add new_field_id int (5) unsigned default 0 not null auto_increment, add primary key (new_fie

add index (ID) 3. Modify the ID field in the table employee as the primary key. Alter table employee add primary key (ID) 4. Modify the ID field in the table employee as the UNIQUE index UNIQUE. Alter table employee add unique (I

Employee table to salary and set its data type to int ALTER TABLE Employee Change ID salary INT 6, delete the customer_id field in the Employee table ALTER TABLE Employee DROP customer_id 7. Delete all primary keys in employe