sql oracle case statement in where clause

1. IF ELSEcannot be used in select, only blocks, such as:IF ...BEGIN...ENDelse (note that there is no else if, to be implemented can only be judged in the following block)BEGIN...ENDReference: Https://msdn.microsoft.com/en-us/library/ms182587.aspx2. Case and then ELSE ENDCan be used in select, but include end endCase ...When ... Then ...ELSE ... (can be omitted)ENDReference: Https://msdn.microsoft.com/en-us/library/ms181765.aspxSQL Server Judgment

Common SQL change and query statements Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/-->Select *, (case when type = 1 then (Select typename from tableatype where type = 1) When type = 2 then (Select typename from tableatype where type = 2) When type = 3 then (Select typename from tableatype where type = 3) Else (Select typename from tableatype where type = 4

connection technologies and index design specifications, each table connection is efficient, and it is reasonable to connect multiple tables. In turn, if you do not understand the Oracle table connection technology and adaptation scenarios, even the connection between the two tables will fail. More pragmatic This title is harsh and even mean, but it is true that I feel it. The domestic IT market does not have such a normal phenomenon: in the face

teminalConn Sys/password as Sysdba Sqlplus--Login without revealing the passwordEnter User-name:sysEnter Password:password as Sysdba--the AS SYSDBA clause must be added to the login with the SYS user Sqlplus Scott/[email Protected]--Non-admin user Login Desc v$database; --Querying the table structure of the V$database database --Execute SQL script in Sqlplus, the following two ways can beSTART file_name@f

SQL Server, db2, and oracle Stored Procedure dynamic SQL statement example Oracle Create or replace procedure a_testAS t_ SQL VARCHAR2 (2000); t_a VARCHAR2 (20); t_ B VARCHAR2 (20); t_c VARCHAR2 (20); t_d VARCHAR2 (20); BEGIN t_c

SQL server, db2, oracle Stored Procedure dynamic SQL statement example, db2oracle Oracle Create or replace procedure a_testAS t_ SQL VARCHAR2 (2000); t_a VARCHAR2 (20); t_ B VARCHAR2 (20); t_c VARCHAR2 (20); t_d VARCHAR2 (20); BE

)The results and execution time of the preceding four sqls are the same after ORACLE analysis, but the principle of shared memory SGA from ORACLE is as follows,It can be concluded that ORACLE will analyze each SQL statement and occupy the shared memory,If the

Obtain SQL statement execution plans from the most authoritative Oracle Database This document is compiled and summarized based on relevant information. It mainly describes the most authoritative and correct methods and steps for obtaining SQL statement execution plans in

indexed character data. This also makes it impossible for the engine to take advantage of indexes. See the following example: SELECT * from T1 WHERE NAME like '%l% ' SELECT * from T1 WHERE substing (name,2,1) = ' L ' SELECT * from T1 WHERE NAME like ' l% ' Even if the Name field is indexed, the first two queries are still unable to use the index to speed up the operation, and the engine has to do a single operation on all of the data in the entire table. A third query can use indexes to sp

) Select the connection sequence, select which table to connect to ORACLE for multi-Table connection, and select which table in the two tables as the basic data table. 8) Select the data search path and select the appropriate data search path based on the preceding conditions. For example, select full table search, index or other methods. 9) run the "Execution Plan" You can use the following statement to qu

: MI: SS 'yyyy', 'mm', 'dd', 'hh12', 'hh24', 'mi', and 'ss; ■ Changing the date format in DB2: Current timestamp 'current date', 'current time', and so on; NOTE 2: ■ Changing the Data Type of SQL Server to "data type parameters": int and varchar; ■ Oracle Data Type Change functions: to_char (), to_date (), to_number (), and so on; ■ DB2 data type change functions: varchar (), INT (), date (), time (), etc;

This article describes in detail how to find and solve SQL statement execution efficiency problems in Oracle. I. methods for identifying statements that occupy a large amount of resources (4 methods)1. Problems Related to slow response reported by the test group and end users.2. Use the V _ $ sqlarea view to provide execution details. (Number of executions, disk

filter row, having filter group, having support all the where operators the --1. In the EMP table, list positions with a minimum wage value of less than 2000. Bayi SELECTJobMIN(SAL) the fromEMP the GROUP byJob - having MIN(SAL) -; - 2List of departments and work-mix combinations with average wage greater than $1200 the SELECT * fromEMP; the SelectDeptno, Job,avg(SAL) the fromEMP the Group byDeptno,job - having AVG(SAL)> - the ORDER byDeptno,job the 3average wage of a department with

1. In the WHERE clause: 1 create TABLE ' hello '. ' Sometbl ' ( Span style= "color: #008080;" > 2 3 ' id ' INT not NULL auto_increment, 5 6 7 ' B ' VARCHAR NULL, 8 9 ' C ' VARCHAR NULL, 10 11 PRIMARY KEY (' id '), 12 13 UNIQUE INDEX ' Id_unique ' (' id ' ASC); 1 INSERT into' Hello '. ' Sometbl ' (' A ', ' B ', ' C ')VALUES('1','1','0');2 3 INSERT into' Hello '. ' Sometbl ' (' B ', ' C ')VALUES('1','1');4 5 INSERT into' H

SQL> showparameter SQL NAME TYPE VALUE ----------------------------------------------------------------------------- Plsql_ccflags string Plsql_code_type string INTERPRETED Plsql_compiler_flags string INTERPRETED, NON_DEBUG Plsql_debug boolean FALSE Plsql_native_library_dir string Plsql_native_library_subdir_count integer 0 Plsql_optimize_level integer 2 Plsql_v2_compatibility boolean FALSE Plsql_warnings s

/gravity /center ">Found two commands together, namely student and where are connected together. So when you use the a command to add a command to the buffer to hit two return, the first carriage return is a command must take the carriage return, the second carriage return is added as the beginning of the new code to the buffer, for example:Q: Suppose the buffer has 3 rows of SQL commands, you need to join the command on the second line. How does it w

Case statement Syntax:--Simple case function Sexwhen ' 1 ' then ' Male ' when ' 2 ' then ' women ' else ' other ' END--case search function Case if sex = ' 1 ' Then ' man ' when sex = ' 2 ' Then ' women ' else ' other ' ENDFirst, create a users table that contains Id,name,se

Although the ORM mapping is used in the project, the optimization of the Oracle system is valuable, which summarizes the commonly used statements from the perspective of SQL statements.1. Optimizations in the From field:Oracle Yasuteru Load table data from right to left, and the tables that can exclude the most data should be placed behind (the underlying table).For example, in the context of the query, put

What exactly does Oracle do when it submits an SQL command to Oracle? A good understanding of this problem can help you better analyze the optimization of SQL statements.Executing an SQL statement from start to finish requires 4 s

In ORACLE, the SQL statement that uses rownum for paging and sorting previously used to use the following SQL statement: select * from (selectt. *, rownumrow_numfrommytabletorderbyt.id) bwhereb. row_numbetween1and10 results show that the order by