sql oracle case statement in where clause

SQL statement for querying Oracle table data by PAGE The SQL syntax for querying Oracle data by page is widely used on the Internet. This article is also a typical syntax for the author to search on the Internet. It is not my original one and is posted here, this is purely t

Syntax for adding fields: alter table tablename add (column datatype [default value] [null/not null],...); Alter table tablename modify (column datatype [default value] [null/not null],...); Syntax for deleting a field: alter table tablename drop (column ); Multiple columns are separated by commas. Use alter table to add, delete, and modify a column. Create a table structure:Copy codeThe Code is as follows:Create table test1(Id varchar2 (20) not null );Add a field:Copy codeThe Code is as follows

while, but recently it became top SQL. In other words, although it was previously top SQL, it has recently become TOP 1. In this case, we can compare the historical execution plans of SQL statements to analyze the causes of slow SQL statements or changes in the execution pl

By default, SQL Server queries are case-insensitive. That is, whereaABC is the same as wherea 'abc '. By default, SQL Server queries are case insensitive. That is, where a = 'abc' is the same as where a = 'abc '. However, we can determine whether the case is

SQL statement implementation that limits the number of data queries in ORACLE and SYBASE databases I. OverviewFor some software that needs to deal with a large amount of data through databases, processing performance is very important. In order to ensure that the software can process all data without crashing, the idea of batch processing came into being. The spe

SQL statement implementation that limits the number of data queries in ORACLE and SYBASE databases. oraclesybase I. Overview For some software that needs to deal with a large amount of data through databases, processing performance is very important. In order to ensure that the software can process all data without crashing, the idea of batch processing came int

Generally, the database processes SQL statements through three processes: parsing (parse), executing (exec), and returning results (fetch) 1. Resolution When a user initiates an SQL statement, Oracle receives the SQL statement to

Oracle 10g SQL paging query statement and Efficiency Analysis When using the Oracle database for paging query algorithm design, the paging query SQL statements can basically be applied according to the template given below:Paging Query format:SELECT * FROM(Select a. *, ROWNU

WangWu 21 A1003 ZhouLiu 22 A1004 SunQi 22Note that after you set the number of query bars to 5 and the query succeeds, you must have a "SET ROWCOUNT 0" statement, or you can return up to 5 data at the next execution.For example, we first execute the following statement:set5selectfrom tb_employeeinfoThe result returned is the same as above.Then execute the following

execution is performed from top to bottomSELECT *From Student_info si--Student Information FormWhere si.school_id=10--academy IDand si.system_id=100--System IDWhen placing a WHERE clause, place the condition that can filter large amounts of data at the bottom8. Optimizations in the From field:Oracle Yasuteru Loading table data from right to left, you should put the table that can exclude the most data to the back (base table) . For example, in the co

system roles mentioned earlier----connect, resource, and DBA, users can also create their own role in Oracle. User-created role can consist of table or system permissions or a combination of both. In order to create role, the user must have the Create role system permission. An example of the Create role command is given below: Copy Code code as follows: Create role student; This command creates a role named student. Once a r

Tags: style blog http ar color SP data div ArtOriginal link http://database.51cto.com/art/201004/192790.htmThe following article focuses on SQL statements that describe Oracle replicated tables, including how to replicate the table structure of SQL.And how to copy the structure of the related table and copy the data SQL in the table.as follows, table A is a table

$ session where sid = '20140901 ';Query the corresponding SQL statement based on the sidSelect SID, SQL _TEXT from v $ open_cursor where SID = '000000 '; 20. View wait StatusSELECT v $ waitstat. class, v $ waitstat. count, SUM (v $ sysstat. value) sum_valueFROM v $ waitstat, v $ sysstat WHERE v $ sysstat. name IN ('db block gets ','Consistent gets') group by v

after the while is true, the loop weight statement sequence is executed 1 times, and then the expression after the while is re-determined to be true, only if the Boolean expression after the while is false. To end the entire loop loop. The syntax for the statement structure is as follows: [ C, while ... Loop structure Sql>--while...loop

I. Case Study A database has two tables about employee information, salary, and department information of a company. They are EMP and dept tables. The structure of the two tables is as follows: The requirements are as follows: 1. Create a corresponding table according to the structure of the table above, and write 5 combination data into each table. 2. The related table is manipulated to increase the salaries of employees in the "Technical Department"

Cited:To illustrate this, a score table is created, as shown in:Comparison:1, in SQL, these two functions we can only use case, the code and the results are as follows:Select Name,Case SubjectWhen ' Chinese ' then 1When ' math ' then 2When ' English ' then 3--else 3End as ' account code 'From ResultsSimilarly, we can use case