oracle sql by example

Database access (DAO)YII contains a data access layer (DAO) built on top of the PHP PDO. DAO provides a unified set of APIs for different databases. Where ActiveRecord provides interaction between the database and the model (M,model in MVC), QueryBuilder is used to create dynamic query statements. DAO provides simple and efficient SQL queries that can be used in various places that interact with the database. YII supports the following databases (DBM

Oracle queries the average SQL Execution time (Code instance) through the v $ SQL view, oraclesqlOracle queries the average SQL Execution time (Code instance) through the v $ SQL View) SELECT SQL _TEXT, EXECUTIONS total EXECUTIONS

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

By separatingSQL statement for local range data scanning Generally, it is more effective to put all components of an SQL statement that implements a function together. However, in a few cases, the SQL separation method is more effective. This situation mainly exists in that when you query two tables with a 1: M relationship, the data used to filter the condition for the "M" side comes from the "1" side. Gen

TransactionsAs the basic unit of logical processing, it is composed of one or more SQL statements for database operations . Of course, there is a good application for non-database operations, such as a restore point set on a computer. The basic nature of the transaction is described in another article: SQL Transactions and example demonstrationsOracle and

the contents of the SQL buffer to check if your modifications are correct. Example 3-8 Sql> L Example 3-8 results Example 3-8 results table name The changes you made are accurate. So how do we run this statement?3.4 '/' (RUN) commandYou certainly do not need to reenter t

Oracle trigger troubleshooting example Routine checks on the AWR Report of the database. An update statement is executed multiple times for over 30 seconds each time. This SQL statement is very simple, that is, modifying data based on primary key conditions, the number of primary keys ranges from 1 to 100. This problem has been around for a long time and only occ

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

Organization Name " Figure 5: Child Department column TipsIn this way, we can deploy the hints we have made to the dashboard test, 6 and Figure 7. Summary: report and Analysis (BI development) Small details create a double hint and have a parent-child association (for example, department and sub-department tips), mainly describe the use of the expression variables to build departments and sub-departments two tips, and to give parent-child a

Oracle tablespace growth exception solution: Another example Description: The temporary tablespace of a database in the customer environment increases abnormally (with a random date). It may be caused by the scheduled jobs of the following two Oracle databases,Time: around, January 14AMThe known growth time of the temporary tablespace is consistent with the error

(DECODE (deptno,20, ' D20 ')) "COUNT-20",SUM (DECODE (deptno,10,sal,null) "SUM-10",SUM (DECODE (deptno,20,sal,null) "SUM-20"from EMP;3-15. Delete duplicate recordsThe most efficient way to delete duplicate records (because ROWID is used)DELETE from EMP EWHERE e.rowid > (SELECT MIN (X.ROWID)From EMP XWHERE x.emp_no = e.emp_no);3-16, reduce the amount of the table queryIn the SQL statement that contains the subquery, pay particular attention to reducin

operation, killed is labeled as kill;Server: Types of servers, dedicated private, shared sharing, etc.;schema#: Schema ID value, the schema# of Oracle internal processes is 0;SCHEMANAME: Schema user name, Oracle internal process for SYS;Osuser: Client operating system user name;Process: Client operating system processes ID;Machine: Operating system name;TERMINAL: Operating system terminal name;Program: Ope

Oracle Export Import table (. SQL,. dmp file) two methods,. SQL. dmp Two ways to export an import table (. SQL and. dmp files) from Oracle Method 1: Export and Import SQL files Export procedure 5. Select the table for data export

floor and floor (n) values are the largest integers less than or equal to the value n (SQL can also be used)The length function in oracle is len in SQL Server.In oracle, The datalength function in sqlserver is datalength.Change the lob_to_char function in oracle to convert

If you are a beginner in Oracle multi-Table query optimization and do not know much about the actual application of Oracle multi-Table query optimization, the following articles will provide you with more comprehensive knowledge. The following is a detailed description of the article. Oracle uses the bottom-up sequence to parse the WHERE clause. According to this

Oracle lock table troubleshooting example One time a developer directly runs the delete table operating system on the database server during peak hours, resulting in no response for a long period of execution. Then, the SQLPLUS client is closed and the delete statement is run again, this causes the database to run slowly.The query operation knows that it is caused by the lock table and is finally processed.

SQL Server gets the first record in each group In daily life, we often need to record some operations, similar to the operation of the log, the last record is valid data, and maybe they belong to different aspects, functions below, from the terminology of the database, is to find a piece of data in each group. Here's what we're going to do is implement the first piece of data from each group in SQL Server.

In Oracle10g, if the installation example is not selected during instance creation, you can create an instance using the script under $ ORACLE_HOME/demo/Schema after the instance is created. For details about the creation method, the official documentation provides the following details: Sampleschema scripts and object descriptions Http://download.oracle.com/docs/cd/B19306_01/server.102/b14198/scripts.htm#sthref77 There are also related creation scri

Label:Select Tools > Preferences > Options > Under plsql Developer: "Oracle Home" and "OCI Library"oracle10g in D:/oracle/oracle home for d:/oracle/product/10.1.0OCI Library for D:/oracle/product/10.1.0/db_1/bin/oci.dllRestart Plsql Developer after configuration, login succe

Import SQL files into powerdesigner (convert Oracle SQL files to MySQL) Set xxxxxx. the procedure for importing the database structure of the SQL file to powerdesigner is as follows: Step 1: export the table structure (no table data, as long as the table structure) of all tables in the database to be imported