oracle sql for dummies

1. select an appropriate ORACLE optimizer 2. Access Table 3. Share SQL statements 4. Select the most efficient table name sequence (only valid in the rule-based Optimizer) 5. The connection sequence in the WHERE clause. 6. Avoid '*' in the SELECT clause '*' 7. Reduce the number of database accesses 1. select an appropriate ORACLE optimizerThere are three optim

/9D/FB/wKioL1mJgPzyH_ Araabn5wfyjxi467.jpg-wh_500x0-wm_3-wmp_4-s_216741007.jpg "alt=" Wkiol1mjgpzyh_araabn5wfyjxi467.jpg-wh_50 "/>Related view important fieldsV$sqlareaV$sqlareav$sql and V$sqlarea are basically similar, and v$sqlarea is more commonly used, so only the V$sqlarea characters commonly used section of the description, as follows (personal reference to Oracle Official document translation, due to

for SQL optimization are emerging, writing your own SQL tools is always the best way to solve the problem:Select executions, disk_reads, buffer_gets,Round (BUFFER_GETS-DISK_READS)/buffer_gets, 2) hit_radio,Round (disk_reads/executions, 2) reads_per_run,SQL _textFrom v $ sqlareaWhere executions> 0And buffer_gets> 0And (BUFFER_GETS-DISK_READS)/buffer_gets Order by

Syntax for building functionsCreate or Replace function name (parameter input or output parameter type) return data typeis return value data type of return valueBeginAction to be done by the functionEndSQL Statement Demo:Create or Replace function My_fun (in_no in number) is Out_name VARCHAR2 (64);BeginSelect Ename to Out_name from EMP where emp.empno=in_no;return out_name;End My_fun;Note: There is no longer end my_fun and end;Function call:DeclareVar_name VARCHAR2 (32);BeginVar_name:=my_fun (73

Invoking Oracle's stored procedures and JDBC operations in Java is similar to the following steps1: Load Driver2: Link database and get a database link object3: Execute statement4: Operation result set5: Close ResourceThe premise is that the stored procedure is written.Create or replace procedure My_procedure isBeginINSERT into EMP (empno,ename) VALUES (9527, ' Tong Pak Fu ');EndJava Program Demo:Import java.sql.CallableStatement;Import java.sql.Connection;Import Java.sql.DriverManager;Import ja

Oracle uses TRACE for SQL Performance Analysis If the SQL _trace parameter is set to true, the entire instance will be tracked, including all processes: User processes and background processes, which may cause serious performance problems and must be used with caution in the production environment. 1. perform trace operations based on related transactions or

Oracle SQL * Loader architecture 1. SQL * Loader architecture SQL * Loader controls the description of the entire load by an input control file, one or more data files are used as raw data, its detailed composition structure includes Input Datafiles --> Loader Control file, the original data File loaded to the database

1. Oracle startup and Shutdown 1. In a single-host environment To start or shut down the Oracle system, you must first switch to the Oracle user, as shown below: Su-Oracle A. Start the Oracle SystemOracle> svrmgrlSvrmgr> connect internalSvrmgr> startupSvrmgr> quit B. D

Oracle Performance Analysis 1: Enabling SQL tracking and obtaining trace files when Oracle queries encounter efficiency problems, we often need to understand the problem so as to provide solutions to the problem. Oracle provides the trace information for SQL Execution, inclu

lot of internal work: parsing SQL statements, estimating index utilization, binding variables, and reading data blocks; (5)You can reset the arraysize parameter in SQL * Plus, SQL * forms, and Pro * C to increase the retrieval data volume for each database access. The recommended value is 200. (6)Use the decode function to reduce processing time: Use t

Background Software Programming in Jiri GA is fascinating: getting started with Database Transaction Processing (suitable for beginners)ArticleThe difference between ms SQL Server and Oracle in Database Transaction Processing caused some controversy, So I recorded my thoughts on database transaction processing. Introduction This article describes the differences between ms

Oracle|server The T-SQL is the language engine of Plsql, while Oracle's language engine is the same. Both of these query languages extend the ANSI SQL-92 standard to provide additional support. Almost all of the applications you create use these supplemental features. This article describes the most common, non-standard Oracl