oracle sql by example

Oracle SQL * plus is a client tool that interacts with oracle. In SQL * plus, you can run the SQL * plus command and the SQL * plus statement. The DML, DDL, and DCL statements we usually call are

Transaction processing is a key issue for all large database products. database vendors have spent a lot of energy in this aspect, different transaction processing methods may cause huge differences in database performance and functions. Transaction processing is also a problem that must be deeply understood by database administrators and database application developers. Negligence on this issue may lead to application logic errors and inefficiency. Next we will discuss some of their differences

Example of recursive calling of stored procedures in SQL Server: SQL Server Stored Procedure Recursion refers to the situation where a code snippet calls itself. The danger lies in how to prevent it from repeatedly calling itself if it calls itself once. That is to say, recursive tests are provided to ensure that exceptions can be obtained when appropriate. A c

Tags: col program configuration SQL query field positioning Rod AC MVCThese days encountered two problems, are very wonderful, distressed for three days, the final positioning out.Problem one, inserting data through PL/SQL developer to a remote Oracle database server, querying data through PL/SQL developer queries, but

are four modules: Fleet information Management, warship information management, military officer information management, weapon information management, and in the four systems to be inserted, query, modify and other changes. Based on these analyses, the data flow chart is drawn out, the dictionary is written out, and the corresponding CDM,LDM,and PDM are drawn using Power Designer . Create a table space, create a user, assign permissions, create a user profile, and then build tables, views,

Cause of SQL Text "** SQL Text Not Available **" in the Oracle ash Report: oracleash Guess: Why "** SQL Text Not Available **" appears in SQL Text in the Oracle ash report The HVR data synchronization software is being tested toda

Many people, especially those who do not like Oracle, must learn from Oracle and think that Oracle occupies a lot of memory.I really don't like installing oracle on a physical machine. Most of them are Windows users, and most of them are developers.Based on the above requirements, I provide a solution:Attach an

Oracle SQL handler, yesDesigned for Oracle database developers and operatorsA carefully crafted Oracle client tool:Ultra-intelligent SQL Editor;Ultra-convenient table operations(You can update the data warehouse table by modifying the cell data of the table );Export data in

DEPT_NO, DEPT_NAME from dept d, EMP E Where d. DEPT_NO = E. DEPT_NO (Efficient ): SELECT DEPT_NO, DEPT_NAME from dept d where exists (SELECT 'x' From emp e where e. DEPT_NO = D. DEPT_NO ); (19) SQL statements are written in upper case, because oracle always parses SQL statements first, converts lowercase letters to uppercase letters, and then executes (20) try t

"Previous topic" column conversion 1--Introduction of Pivot and Unpivot function Implementation case1001 Lufei1001 Shanzhi1001 Namei1001 QiaobaThe implementation results are as follows:1001 Lufei,shanzhi,namei,qiaobaTypical row and column conversions: There are many ways to achieve this. The Listagg function is provided after oracle11g, which is best used to achieve the above effect; let's see Listagg syntax.The syntax structure of the LISTAGG function is as follows:>listagg ([,]) wi

clause: Oracle converts ' * ' to all column names in the parsing process, which is done by querying the data dictionary, which means more time will be spent (4) Reduce the number of accesses to the database: Oracle has done a lot of work internally: Parsing SQL statements, estimating index utilization, binding variables, reading chunks, etc. (5) Reset the ar

numeric field A, and 0.3 million records A = 3.Therefore, the effect of executing A> 2 and A> = 3 is very different, because ORACLE will first find the record index of 2 and then compare it, when A> = 3, ORACLE directly finds the record Index = 3.6. LIKE OperatorThe LIKE operator can be used for wildcard queries. The wildcard combinations in the LIKE operator can be used for almost any queries. However, po

Oracle sqlplus login. SQL settings, sqlpluslogin. SQL Sqlplus automatically runs two scripts at startup: glogin. SQL and login. SQL. The execution order is 1. The glogin. SQL file is searched for and executed in the $ ORACLE_HOME/

How to use dynamic SQL in oracle development in general PL/SQL programming, SQL can be directly used in DML and transaction control statements, however, DDL statements and system control statements cannot be directly used in PL/SQL. To use DDL statements and system control s

Assume that you have a network ordering system based on Microsoft. NET, but the QC maintenance system still uses an old Oracle database application. If your customer places an order such as product replacement during the warranty period, the order will not be charged. In this case, you need to obtain real-time query results from the Oracle database. By establishing a link server (linked Server), you can que

Mysql and oracle batch processing run SQL file and oracle import dmp file bitsCN.com Mysql and oracle batch processing run SQL files and oracle import dmp files Mysql batch run SQL

MySql batch insert optimization SQL Execution efficiency example details, SQL Execution Efficiency Detailed description of MySql batch insert optimization SQL Execution efficiency instances The number of itemcontractprice is about 10 thousand. Five logs are inserted for each itemcontractprice. UpdateInsertSql. appendFo

indexed. Therefore, some qualified data may not be found during query. In count (expr), nvl (column name, 0) is used for processing and then query.G. The sorting time is larger than other data (the index is sorted in descending order by default, small → large), so the NULL value is always at the end.Is null and is not null are an integral whole. Changing to IS or is not is incorrect. We can see the difference between NULL and NULL strings from the above. Any comparison operation with NULL, such

Oracle BASICS (1): Use the oracle instance and SQL * plus commandI. Three-tier structure of oracle Database1. Client: used to access databases. Such as sqlplus and pl/SQL dev. 2. database Server-oracle dbms (database management sy

Tns_admin and the value is the path to the Tnsnames.ora file, for example: E:\oracleclient\instantclient_11_24.After installing Plsql, start, Cancel, and click Tools->preferences->connection:Oracle home=e:\oracleclient\instantclient_11_2OCI Library=e:\oracleclient\instantclient_11_2\oci.dllRestart Plsql, enter the user name, password, select the PL/SQL instance name to enter the database5.The initial login