Skip to main content

Case statement in SQL Server

SQL Server gives us facility to fetch or modify records on condition basis. Suppose we have an “Order” table and we need to fetch records with conditions if user order price is less than 200 Rs it means user is “silver”, if price is greater than 200Rs and less than 500Rs it means user is Gold same like this if price is greater than 500Rs it means user is “Platinum” .

We can easily solve this problem using SQL Server.

Example:


CREATE TABLE #Order(
ID INT IDENTITY(1,1) PRIMARY KEY,
USR_NAME VARCHAR(100),
SKU VARCHAR(100),
QTY INT,
PRICE DECIMAL(18,2),
CREATED_DATE DATETIME
)

INSERT INTO #Order (USR_NAME,SKU,QTY,PRICE,CREATED_DATE)
SELECT 'User1','9876543210',2,200,GETDATE()
UNION ALL
SELECT 'User2','9876543210',2,300,GETDATE()
UNION ALL
SELECT 'User3','9876543210',2,400,GETDATE()
UNION ALL
SELECT 'User4','9876543210',2,550,GETDATE()

--Case statement
SELECT USR_NAME,PRICE,
(
            CASE
            WHEN PRICE<=200 THEN 'SILVER'
            WHEN PRICE>200 AND PRICE<=500 THEN 'GOLDEN'
            WHEN PRICE>500 THEN 'PLATINUM' ELSE 'NULL' END 
) AS USER_TYPE
FROM #Order

DROP TABLE #Order



 The basic formulations for CASE Expression

Simple Case Expression: Simple case expressions check one expression against multiple values. Simple case expressions allow only an equality check.

Example:


DECLARE @value INT=2
SELECT CASE @value WHEN 1 THEN 'ONE'
                                                   WHEN 2 THEN 'TWO'
                                                   WHEN 3 THEN 'THREE'
                                                   ELSE 'NOT MATCH'
                                                   END


Searched Case Expression: Searched Case Expression allows comparison operators. The simple CASE expression checks only for equivalent values and can’t contain Boolean expressions.

Example:



DECLARE @value INT=20
SELECT CASE WHEN @value<20 THEN 'SILVER'
                     WHEN @value>=20 AND @value<=50 THEN 'GOLDEN'
                     WHEN @value >50 THEN 'PLATINUM'
                     END

Popular posts from this blog

Query to find stored procedures by nested stored procedure name

Problem: Suppose we have a stored procedure which has been used in several stored procedure, I mean stored procedure usp_proc1 is nested in many stored procedures like below
BEGIN DECLARE@ResultTABLE ( IDINT, NAMEVARCHAR(50), [ADDRESS]VARCHAR(255) ) INSERTINTO@Result EXECusp_proc1@Name='codefari' END
So I want to find all those queries who containing usp_proc1
Solution: There is a lot of solutions, I'm giving some of them below. If you want to get the only name of the stored procedures then use the following query. Using join query on system tables syscomments and sysobjects we can get the stored procedures name which containing the particular table, nested procs or any other string.
SELECTDISTINCTo.name FROMsyscommentss INNERJOINsysobjectsoONs.id=o.id

Check for changes to an SQL Server table?

Problem: Suppose your team is working on the under-development project so it might be possible continuous work on the database and perform changes in Table, Stored procedure as per requirement, and daily you have to update the testing server database as per changes are done in developing server database then how it is possible to trace those changes. There are a lot of solutions for this problem which is listed below Solution 1: For SQL Server 2000, 2005 and above use the CHECKSUM command SELECTCHECKSUM_AGG(BINARY_CHECKSUM(*))FROMYour_Table_NameWITH (NOLOCK); That will return the same number each time its run as long as the table contents haven't changed. Unfortunately CHECKSUM does not work always properly to detect changes. It is only a primitive checksum and no CRC calculation. Therefore you can't use it to detect all changes, e. g. symmetrical changes result in the same CHECKSUM! Solution 2: 1.Run the following query. Before executing query replace DB_Name with your database name…

Merge and Merge join transformation in SSIS

MERGE TRANSFORMATION
Using Merge Transformation we can combine two sorted data-set into single data-set basically Merge Transformation used to combines rows from two sorted data flows into one sorted data flow. Following tasks you may perform using Merge Transformation: 1.Suppose we have a scenario like, we need to merge data from a database table and excel means we want to merge data from two different data sources. For such type of scenario, you can use Merge Transformation. 2.If we want to merge data from two same structured tables but exists two different servers. 3.Sometimes we get an error due to data in a row, after correcting errors in the data we can re-merge rows easily. See below explanations may help you to understand Merge Transformation: I do evaluate here, you already know about the data source, data conversion, data flow, task flow, control flow etc. Note:Before Merge transformation, we need to sort the data using Sort Transformation. After sorting data add data path to Merge…