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 ...
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...
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: SQL (Structured Query Language) (sql) In this statement: First, you specify the name of the table, to which you want to add the ...
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_money number(9,2) ); 修改一个字段 代码如下...
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; ...
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’; ...
ALTER TABLE old_table_name RENAME TO new_table_name;(大写为系统命令) 2:使用rename修改 SQL> select tname from tab ; TNAME ——— TEST SQL> rename test to temp ; Table renamed. SQL> select tname from tab ; TNAME ——— TEMP 注意: rname只能修改自己schema下面...
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...
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; ...
每种补偿日志返回一行,结果中需要包含ALL COLUMN LOGGING,或者PRIMARY KEY LOGGING和UNIQUE KEY LOGGING都包含。 如果未打开表级别的补偿日志,请执行下述语句。 ALTERTABLEtable_nameADDSUPPLEMENTAL LOGDATA(PRIMARYKEY,UNIQUE)COLUMNS; 打开后,切换 2 次归档日志,并且启动任务前需要等待 5 分钟以上。如果是 Oracle RAC...