SQL Case When Statement

The switch used in the CASE function programming languages ​​is similar to the Swtich Case, Select Case structures. Actually, we can say the same thing. Of course, the decision structure here does not lead to a conclusion, but the conditions that provide any condition allows us to show the way we want. In SQL, the CASE function is used in two ways. These are called simple Case and searched case.

Name Control:

SELECT DISTINCT Name,
CASE Name
	WHEN 'furkan' THEN 'I'
	WHEN 'osman'  THEN 'Father'
	WHEN 'zeynep' THEN 'My girlfriend'
	WHEN 'fatma' THEN 'Mother'
	ELSE 'I dont know'
END as info
FROM personel.dbo.Personeller
ORDER BY Name asc;

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Age Control

SELECT DISTINCT Age,
CASE
	WHEN Age< 20  THEN 'Young'
	WHEN 20 < Age and Age < 30  THEN 'Young Adult'
	WHEN 30 < Age and Age < 50  THEN 'Adult'
	WHEN 50 < Age THEN 'Old'
	ELSE 'Hımmm'
END as info
FROM personel.dbo.Personeller
ORDER BY Age desc;

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SQL TABLE

Name	Surname	ID	Hometown	Age
Ali	kaya	1254	sinop	21
mehmet	nazmi	1247	artvin	26
osman	yazar	1578	hakkari	35
fatma	gündogdu	8972	ankara	19
irem	yazar	4574	yalova	23
idil	kirmizi	1258	antalya	25
furkan	gulsen	1453	sinop	21
zeynep	gozhan	1881	yozgat	19
suheyda	kaya	3647	izmir	28
galip	kose	8362	ankara	24
mehmet	kucuk	2617	konya	22
nazmi	kucuk	8595	mardin	25
ayse	gul	1546	ankara	26
ertugrul	gazi	1884	bursa	32
zeynep	kalin	4768	izmir	27
sumeyra	gulsen	5264	sinop	31
muhammed	aski	4578	istanbul	24
burkay	yazici	8195	artvin	42
buray	testereci	2563	ankara	35
seren	gelin	6985	mardin	41
osman	topaloglu	9274	hakkari	55
pelin	semt	1048	usak	49
kubra	buyuran	4892	izmir	38
samet	yesildag	7382	sivas	39
selin	ozkan	3894	antalya	33
samet	kalin	4828	edirne	28
sabri	isik	5848	trabzon	45
mahmut	tuncer	4838	mardin	55
busra	kiraz	9205	agri	52
huseyin	manti	6392	rize	39
huseyin	abile	2045	hatay	18
kemal	yanardag	4983	canakkale	32
yamac	kosavalı	7282	istanbul	26
vartolu	sadattin	4930	bursa	23
mehmet	kirbiyik	9398	sanliurfa	21
teker	selim	2102	mardin	36
busra	belil	7420	konya	27
nazmiye	kilic	5829	balikesir	18
yavuz	karaselim	8529	canakkale	37
selim	figen	2791	artvin	62
ekrem	bola	8532	edirne	36
mehmet	kamil	1939	sivas	24
kamil	sedet	3953	yozgat	31
yavuz	karasu	7420	konya	45
ibrahim	kaptan	2350	canakkale	39
nurgul	kizil	4930	sivas	23