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To change the default value of a large table, use alter table instead of recreating the table. frm executes most of the modification operations in mysql. It needs to recreate a table, p
following example, create a table T. When creating a table, the storage clause specifies that the initial table size is 5 MB,The database block size is 8 KB, so it is equivalent to 5*1024/8 = 640 blocks.With alter table move, the table
Tags: rebuild call dex space Build table Management gem row migrate OracleALTER TABLE t move and ALTER TABLE t shrink space can be used for segment shrinkage, reducing high water HWM,can also be used to eliminate row Chaining and row migration (row migration),But there are the following differences:1) using
columns is a one-time DDL operation that generates a large number of Redo Log records; Data Tables are locked for a long time, which hinders the production system. When a data column is added, an exclusive lock is added to the data table, which hinders other DML operations; Destroys the original storage structure, resulting in a large amount of Row Migration data. When you try to add each data row to the default
Manpower.s_salary 375w record, add field add_sh number (7,2) default 0 1. Excluding the use of the first SELECT P.spid,s.status,s.terminal,s.machine,s.program,s.osuser,s.client_info,s.logon_time from V$SESSION S,V$ ACCESS a,v$process PWHERE S.sid=a.sidand S.PADDR=P.ADDR and a.object= ' S_salary ' 2.alter table Manpower.s_salary Add (add_sh number (7,2)
has been strengthened again, we can not set the NOT NULL here, greatly reducing the possible error operationSee the following experimental processCREATE table T, where more than 1 million rows of data.Sql> Select COUNT (*) from T; COUNT (*)---------- 1454256Add a column directly to the table (not set NOT NULL)Sql> ALTER T
In Oracle, you can specify a default value for a table column. In this way, when you insert data, if the column does not appear in the insert statement, the default value is assigned to it. In
-- 1. Create the test table createtabletab_default (idvarchar2 (2), default_sysdatedate, default_char_datevarchar2 (8), default_guidvar -- 1. create test table tab_default (id varchar2 (2), default_sysdate date, default_char_date varchar2 (8), default_guid var 1. Script and test procedure -- 1. Create a test tableCreate table tab_default (id varchar2 (2), de
This section describes how to use the alter table statement to modify a table. The alter table statement can execute the following tasks: 1. Add, modify, or delete Columns 2. add or delete Constraints 3. enable or disable Constraints 1. Add a column (
CREATE TABLE Space/* divided into four steps *//* Step 1th: Create a temporary tablespace */Create temporary tablespace user_tempTempfile ' D:\oracle\oradata\Oracle9i\user_temp.dbf 'Size 50mAutoextend onNext 50m maxsize 20480m//Assuming maximum value is not capped, use unlimitedExtent management Local; The extent indicates that interval settings are managed in a
Alter table tablename add (column datatype [default value] [null/not null],...); Alter table tablename modify (column datatype [default value
Oracle alter table, oraclealtertable Create table T_CLASS_INFO (CLASSNO number (3) primary key, -- class numberCLASSNAME varchar2 (10 ),CLASSPLACE varchar2 (13));Create table T_STUDENT_INFO (STUNO number (3), -- Student IDCLASSNO number (3 ),STUNAME varchar2 (10 ),STUSEX cha
1. Find out which tables have incorrect tablespaces. Select * From dba_tables where tablespace_name = 'tdb '; 2. Move the tablespace in TDB to tdb2009. Syntax: alter table table_name move tablespace tablespace_name; Alter table tdb2009.assoc _ INFO move tablespace tdb2009;
The following articles mainly describe the actual application code for Oracle to use alter to modify table elements. If you are curious about the actual operation of Oracle to use alter to modify table elements, the following arti
--Create a folder where the path is the alter log pathCreate or ReplaceDirectory Data_dir as'/u01/app/oracle/diag/rdbms/orcl/orcl/trace';--Create an external tableCreate TableAlert_log (Text_linevarchar2(225)) organization external (TYPE Oracle_loaderDEFAULTDIRECTORY data_dir ACCESS PARAMETERS (RECORDS delimited byNEWLINE Fields) Location ('Alert_orcl.log' ));--Querying database startup time SQLSelect
Note: [Oracle problem set] refers to the problems and solutions encountered by bloggers during database operations. Statement execution: indicates the database operation process. Error: Indicates An error occurred while operating the database. Error cause: indicates the cause of the error. Solution: indicates the solution to the error. Related Knowledge: indicates the knowledge related to this topic. ============================================
Label:This article mainly describes the Oracle table add field, delete table fields to modify the use of table, please refer to the use of itSyntax for adding a field: ALTER TABLE tablename Add (column datatype [
,hidden_column3--From User_tab_cols4--where table_name= ' Cb_batch_flow ' and column_name= ' Bfl_oprno '5 6--Description: Modify the steps:7--(1Query the User_tab_cols table first. The column's virtual column data_default the field information, taking the hash value8--(2) if (1) to find the hash value, you need to perform EXEC delete the column of the virtual column operation, if you do not find the hash
Http://dba-oracle.com/t_alter_table_modify_column_syntax_example.htm For complete tips on Oracle ALTER TABLE syntax, click Easy Oracle Jumpstart. Oracle provides "ALTER TABLE" syntax to
Tag: User DDR termination process resource Release lock DBA system use UPDTerminate process mode by operating system mode and Oracle through the For Update lock table--The query needs to terminate the process, including the operating system processSelect Proc.spid,Sess.sid,sess.serial#,Lo.oracle_username,Lo.os_user_name,Ao.object_name,Lo.locked_modeFrom V$locked_object Lo, dba_objects ao, v$session sess,v$p
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