Oracle

% TYPE and % ROWTYPE in Oracle 1. Using % TYPE www.2cto.com in many cases, variables should have the same TYPE as columns. For example, if the name column type of the emp table is VARCHAR2 (20), we can DECLARE a variable: DECLARE var_Name VARCHAR2 (2

Select rpad ('', 4 * (LEVEL-1), '--') | name as name, CONNECT_BY_ROOT name" ROOT ", www.2cto.com CONNECT_BY_ISLEAF" ISLEAF ", LEVEL, t. *, SYS_CONNECT_BY_PATH (t. name, '/') "PATH" from sys_department t start with t. required mentid = 1 connect by

Some time ago, someone asked me about the order adjustment of table fields in the database. First, there is no bad impact on the database. Second, there is no simple method or tool to solve this problem. Www.2cto.com is a common problem for most

Change the "create" statement of oracle to "alter statement" to view a table in PD. Double-click a table and view its preview label. Then, you can find the "create" statement of a table, as shown below: create table Company_Info (www.2cto.com

How to use A user in Oracle to access tables owned by other users if Oracle has two users A and B, then if A wants to access the tables owned by B, the statement should be: SELECT * from B. TABLENAME. Www.2cto.com: Can I modify the Oracle settings

Oracle SQL code www.2cto.com create table test (col VARCHAR2 (20) insert into test VALUES ('A'); insert into test VALUES ('B '); insert into test VALUES ('C'); insert into test VALUES ('A'); insert into test VALUES ('C'); COMMIT; -- DELETE duplicate

An oracle custom exception occurs. After the stored procedure is executed somewhere, an exception Java code www.2cto.com biz_exception exception exists. Then, the SQL code p_RETCODE: = '-1'; p_retInfo: = 'generated salary + Social Security Bill.

The difference between union and union all and the use of join 1. The difference between union and union all is www.2cto.com Union. union operations are performed on two result sets, excluding repeated rows, sort the default rules at the same time.

Oracle (merge query, transaction, and some SQL functions) Table query: www.2cto.com merge query: Use the union keyword to remove duplicate rows that meet the condition. [SQL] select ename, sal, job from emp where sal> 2500 union select ename, sal,

Oracle Special Character Processing if you have a project or product that supports fuzzy search, we recommend that you perform a test: Enter "_" in the search box (underline) or "%" (percentage), and then search to see what results will be obtained.

Oracle parameter shared_pool_size environment: www.2cto.com [html] idle> select * from v $ version; BANNER -------------------------------------------------------------- Oracle Database 10g Enterprise Edition Release 10.2.0.1.0-Prod PL/SQL Release 10

[SQL] www.2cto.com sys @ EMREP> select * from v $ version where rownum = 1; BANNER ---------------------------------------------------------------- Oracle Database 10g Enterprise Edition Release 10.2.0.1.0-Prod sys @ EMREP>! Uname-a Linux localhost.

In RMAN configuration, the relationship between the CHANNEL-related parameters PARALLELISM and FILESPERSET is PARALLELISM --- www.2cto.com. We can also use the parallelism parameter to specify how many channels are automatically created at the same

Oracle get system time, previous day get system time www.2cto.com select sysdate from dual get previous day select sysdate-1 from dual select to_char (sysdate, 'D') day of week, to_char (sysdate, 'dd') day of each month, to_char (sysdate, 'ddd ')

When the data in the table is not required, Delete the data and release the occupied space. To Delete the data in the table, use the Delete statement or the Truncate statement. Www.2cto.com 1. delete Statement (1) conditional deletion syntax format:

1. Two services are not started normally: OracleOraDb10g_home1TNSListener, OracleServiceORCL solution: Run-services. msc, locate the two required services, and start them.Www.2cto.com www.2cto.com2. if the system is started or cannot run, check

Oracle backup and recovery Script 1 backup [plain] @ echo off set oracle_username = sorted set oracle_password = YOUR_PASSWORD set local_tnsname = LOCAL_TNSNAME set url = % oracle_username %/% oracle_password % if not % local_tnsname % = "" set url =

After Oracle is installed on five Windows Services in Oracle, the system creates a series of Oracle services, which can ensure the normal operation of Oracle. In "Management Tools" and "services" in "Control Panel", you can see the following

34 ways for oracle to improve query efficiency 1. Select the most efficient table name order (only valid in the rule-based Optimizer ): the ORACLE parser processes the table names in the FROM clause in the order FROM right to left. The table written

PL/SQL programming method Daquan I. dynamic SQL splicing (using replace) www.2cto.com pay attention to using replace to achieve dynamic SQL splicing effect, v_psql can be used to pass variables [plain] 1 declare 2 a number: = 2; 3 v_ SQL varchar2 (40