ImplementationDELETE

Structured Query Language is used to allow database developers to generate queries and interrogate the data held in a database. SELECT, FROM, WHERE, AND and OR are key areas of SQL.

Part ofComputing ScienceDatabase design and development

DELETE

To delete the record for Tom Glacney, the following SQL would be used:

DELETE FROM Pupil
WHERE First Name = ‘Tom’ AND Surname = ‘Glacney’;

This would return:

PupilIDFirst NameSurnameClassPastoral Care TeacherMerit Points
0001NisaSingh1T1Mr Harley0
0002DavieBoland1I2Mrs Aitken0
0003AmyJones1M1Mr Gilchrist0
0004JamesMcNamee1T1Mr Harley0
0005PawelMcTavish1I1Mrs Aitken0
0006AntoniaGallagher1M2Mr Gilchrist0
0007AmyMcNamee1T1Mr Harley0
0008TabisoMatazinadze1T1Mr Harley0
0009BeatricePanner1T2Mr Harley0
0011FrankieAl-Robeye1M2Mr Gilchrist0
PupilID0001
First NameNisa
SurnameSingh
Class1T1
Pastoral Care TeacherMr Harley
Merit Points0
PupilID0002
First NameDavie
SurnameBoland
Class1I2
Pastoral Care TeacherMrs Aitken
Merit Points0
PupilID0003
First NameAmy
SurnameJones
Class1M1
Pastoral Care TeacherMr Gilchrist
Merit Points0
PupilID0004
First NameJames
SurnameMcNamee
Class1T1
Pastoral Care TeacherMr Harley
Merit Points0
PupilID0005
First NamePawel
SurnameMcTavish
Class1I1
Pastoral Care TeacherMrs Aitken
Merit Points0
PupilID0006
First NameAntonia
SurnameGallagher
Class1M2
Pastoral Care TeacherMr Gilchrist
Merit Points0
PupilID0007
First NameAmy
SurnameMcNamee
Class1T1
Pastoral Care TeacherMr Harley
Merit Points0
PupilID0008
First NameTabiso
SurnameMatazinadze
Class1T1
Pastoral Care TeacherMr Harley
Merit Points0
PupilID0009
First NameBeatrice
SurnamePanner
Class1T2
Pastoral Care TeacherMr Harley
Merit Points0
PupilID0011
First NameFrankie
SurnameAl-Robeye
Class1M2
Pastoral Care TeacherMr Gilchrist
Merit Points0

Using the DELETE statement without a WHERE clause will delete all records held in the table. Both examples shown below would delete all records held in the pupil table.

DELETE FROM Pupil;

Or

DELETE * FROM Pupil;

It is unlikely that a developer would have need to delete all records from a table but it is important to understand that without a WHERE clause the records will all be removed.