Queries
Select All Elements
SELECT * FROM table;Remove Duplicated Elements
SELECT DISTINCT col FROM table;Selection with Conditions
SELECT * FROM mytable WHERE attr = 'something';Comparison Operators
| Operator | Mean |
|---|---|
= | Equal |
<> or != | Not equal |
< | Less than |
> | More than |
<= | Less than or equal |
>= | More than or equal |
<=> | Safe equal |
IS NULL / IS NOT NULL | Equal to NULL |
Only <=> can be used to judge two NULL are equal.
Logical Operators
| Operator | Mean |
|---|---|
AND or && | AND |
OR or ` | OR |
NOT or ! | NOT |
Other Condition Operators
| Operator | Mean |
|---|---|
BETWEEN value1 AND value2 | value1 <= value AND value <= value2 |
IN (...) | In the set (...) |
NOT IN (...) | Not in the set (...) |
LIKE | Fuzzy match. |
REGEXP or RLIKE | Regular expression match. |
Wildcard Match
% can match multiple random characters.
_ can match only one random character.
CONCAT
SELECT CONCAT(col_1, ' ', col_2) 'Alias Name' FROM table;Sort
Default is ascending.
SELECT col_1, col_2 FROM table ORDER BY col_1;Sort in descending order:
SELECT col_1, col_2 FROM table ORDER BY col_1 DESC;Sub Query
SELECT * FROM
(SELECT * FROM table WHERE attr1 LIKE 'A%') AS new_table
WHERE new_table.attr2 LIKE 'AB%';Last updated on