Introduction to Oracle ALTER TABLE ADD column statement To add a new column to a table, you use the ALTER TABLE statement as follows: ALTER TABLE table_name ADD column_name data_type constraint;Code language:
Add a new column to table with theALTER TABLE… ADDstatement. Set the column properties in the same command itself. As an example, add columnc1of data typeINTwith default value of1. Set the column as non-nullable with theNOT NULLclause. Set thec1column as the primary key with thePRIMARY...
Note that thiscan take some time, and that during the update, there is an exclusive DML lockon the table. For some types of tables (for example, tables without LOBcolumns), if you specify both a NOT NULL constraint and adefault value, the database can optimize the column add operation ...
ALTER TABLE tablename ADD columnname AFTER columnname; Oracle does not support this syntax. However, it doesn't mean that it cannot be done. Workarounds: 1. Create a new table and copy the data across. SQL> RENAME tab1 TO tab1_old; Table renamed. SQL> CREATE TABLE tab1 AS SELECT ...
删除字段的语法: ALTER TABLE table_name(MODIFY column_name column_type , ... ); 例子: 使用一个SQL语句同时添加三个字段: 代码如下: 1 2 3 4 5 6 7 altertabletest1 add( namevarchar2(30)default‘无名氏'notnull, ageintegerdefault22notnull, has...
comment on table table_name is ‘comments_on_tab_information’; 2.对表中列的说明 comment on column table.column_name is ‘comments_on_col_information’; 3.查看表的说明 SQL> select * from user_tab_comments where TABLE_NAME=’EMPLOYEES’; ...
在执行add column 之前,我们启用10046 事件跟踪一下这个过程: SQL> oradebug setmypid Statement processed. SQL> oradebug event 10046 trace name context forever,level 8; Statement processed. --执行操作 SQL> alter table t1 add tel varchar2(20)default '13888888888' not null; ...
1、首先建表语法：Create table 表名，字段 1 数据类型 [default 默认值],字段 2 数据类型 [default 默认值],...字段 n 数据类型 [default 默认值]。2、表删除语法：DROP TABLE 表名。3、表的修改，在sql中使用alter，可以修改表，添加语法：ALTER TABLE 表名称 ADD(列名 1 类型 [DEFAULT ...
SQL> selectcount(*) from t; 1000000 SQL> altertable t add add_h number not null; alter table tadd add_h number not null * ERROR at line1: ORA-01758:table must be empty to add mandatory (NOT NULL) column 新增一个仅有NOT NULL约束,没有默认值的字段,则需要表为空。顺带提一句,删除表...
addressvarchar2(100)--学生的地址);--SQL语句结束 我们添加一个 英文状态下的;--添加字段ALTERTABLEt_studentADDgenderchar(3);--修改字段类型ALTERTABLEt_studentMODIFYgendervarchar2(3);--修改字段名称ALTERTABLEt_studentRENAMECOLUMNgender to sex;--删除字段ALTERTABLEt_studentDROPCOLUMNsex; ...