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Annotated edit history of SQL version 9, including all changes. View license author blame.
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7 AristotlePagaltzis 1 [Acronym] for __S__tructured __Q__uery __L__anguage. Some DataBase professionals think the ''S'' should stand for "stupid."
1 PerryLorier 2
7 AristotlePagaltzis 3 [SQL] is a set-centric ProgrammingLanguage in which statements are excuted over a [Schema] of relations (tables), and return a table of results.
2 StuartYeates 4
7 AristotlePagaltzis 5 !! Syntax and examples
3 AristotlePagaltzis 6
7 AristotlePagaltzis 7 In this example, imagine we have a table called <tt>users</tt> which has an <tt>id</tt>, a <tt>name</tt> and an <tt>accesslevel</tt> column.
6 CraigBox 8
9 __Retrieving data:__
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7 AristotlePagaltzis 11 <pre>
9 AristotlePagaltzis 12 SELECT ''col_1'', ''col_2'', ''col_n'' FROM ''table'' WHERE ''condition''
7 AristotlePagaltzis 13 </pre>
14
15 Eg. to find the access level of user number 154:''''
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17 <pre>
18 SELECT accesslevel FROM users WHERE id = 154;
19 </pre>
6 CraigBox 20
21 __Inserting data:__
22
7 AristotlePagaltzis 23 <pre>
8 DavidHallett 24 INSERT INTO ''table'' (''column_one'', ''column_...'', ''column_n'') VALUES (''value_one'', ''value_...'', ''value_n'')
7 AristotlePagaltzis 25 </pre>
26
27 Eg. to add a new user:''''
28
29 <pre>
30 INSERT INTO users (name, accesslevel) VALUES ('Craig', 10);
31 </pre>
32
33 The next available ID number is automatically assigned.
6 CraigBox 34
35 __Updating data:__
36
7 AristotlePagaltzis 37 <pre>
8 DavidHallett 38 UPDATE ''table'' SET ''column_one''=''value_one'', ''column_...''=''value_...'', ''column_n''=''value_n'' WHERE ''condition''
7 AristotlePagaltzis 39 </pre>
40
41 Eg. to set an accesslevel of 15 to everyone whos name starts with a C:''''
42
43 <pre>
44 UPDATE users SET accesslevel=15 WHERE name LIKE 'C%';
45 </pre>
6 CraigBox 46
47 __Removing data:__
48
7 AristotlePagaltzis 49 <pre>
50 DELETE FROM ''table'' WHERE ''condition''
51 </pre>
52
53 Eg. to remove the user with ID number 30:''''
54
55 <pre>
56 DELETE FROM users WHERE id = 30;
57 </pre>
4 AristotlePagaltzis 58
59 ----
7 AristotlePagaltzis 60 Part of CategoryProgrammingLanguages and CategorySpecialPurposeProgrammingLanguages