Usage of MySQLalter statements, adding, modifying, and deleting Fields

Primary Key altertabletabelnameaddnew_field_idint (5) unsigneddefa0notnullauto_increment, addprimarykey (new_fi

// Primary key alter table tabelname add new_field_id int (5) unsigned default 0 not null auto_increment, add primary key (new_fi

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MySQL alter statement usage, adding, modifying, and deleting Fields

[Date: 2010-02-22] Source: MySQL Community Author: MySQL [Font:]

// Primary key

Alter table tabelname add new_field_id int (5) unsigned default 0 not null auto_increment, add primary key (new_field_id );
// Add a new column

Alter table t2 add d timestamp; alter table infos add ex tinyint not null default '0 ';
// Delete a column

Alter table t2 drop column c;
// Rename a column

Alter table t1 change a B integer;

// Change the column type

Alter table t1 change B bigint not null; alter table infos change list tinyint not null default '0 ';
// Rename the table

Alter table t1 rename t2;
Add Index

Mysql> alter table tablename change depno int (5) not null; mysql> alter table tablename add index name (field name 1 [, field name 2…]); Mysql> alter table tablename add index emp_name (name );
Index with primary keywords

Mysql> alter table tablename add primary key (id );
Add an index with unique conditions

Mysql> alter table tablename add unique emp_name2 (cardnumber );
Delete An index

Mysql> alter table tablename drop index emp_name;
Modify Table:

Add field:

Mysql> alter table table_name ADD field_name field_type;
Modify the original field name and type:

Mysql> alter table table_name CHANGE old_field_name new_field_name field_type;
Delete field:

Mysql> alter table table_name DROP field_name;

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