LIKE Operator defined
The LIKE operator is used in a WHERE or HAVING (as part of the GROUP BY ) to limit the selected rows to the items when a column has a certain pattern of characters contained in it.
This guide will demonstrate:
- Determining if a string starts or ends with a given string pattern
- Determining if a pattern exists in the middle of the string
- Determining if a string is not contained in the string
A column starts or ends with a given string pattern
This SQL will select students that have FullName starting with “Monique” or ending with “Greene”.
SELECT studentID, FullName, sat_score, rcd_updated
FROM student
WHERE
FullName LIKE 'Monique%' OR -- note the % at the end but not the beginning
FullName LIKE '%Greene'; -- note the % at the beginning but not the end
+-----------+---------------+-----------+---------------------+
| studentID | FullName | sat_score | rcd_updated |
+-----------+---------------+-----------+---------------------+
| 1 | Monique Davis | 400 | 2017-08-16 15:34:50 |
| 5 | Alvin Greene | 1200 | 2017-08-16 15:34:50 |
+-----------+---------------+-----------+---------------------+
2 rows in set (0.00 sec)
A string pattern is in the middle of the column
This SQL will select students that have “ree” anywhere in the name.
SELECT studentID, FullName, sat_score, rcd_updated
FROM student
WHERE FullName LIKE '%ree%'; -- note the % at the beginning AND at the end
+-----------+----------------+-----------+---------------------+
| studentID | FullName | sat_score | rcd_updated |
+-----------+----------------+-----------+---------------------+
| 5 | Alvin Greene | 1200 | 2017-08-16 15:34:50 |
| 6 | Sophie Freeman | 1200 | 2017-08-16 15:34:50 |
+-----------+----------------+-----------+---------------------+
2 rows in set (0.00 sec)
A string is NOT in the column
You can place “NOT” before LIKE to exclude the rows with the string pattern instead of selecting them. This SQL excludes records that contain “cer Pau” and “Ted” in the FullName column.
SELECT studentID, FullName, sat_score, rcd_updated
FROM student
WHERE FullName NOT LIKE '%cer Pau%' AND FullName NOT LIKE '%"Ted"%';
+-----------+----------------------+-----------+---------------------+
| studentID | FullName | sat_score | rcd_updated |
+-----------+----------------------+-----------+---------------------+
| 1 | Monique Davis | 400 | 2017-08-16 15:34:50 |
| 2 | Teri Gutierrez | 800 | 2017-08-16 15:34:50 |
| 4 | Louis Ramsey | 1200 | 2017-08-16 15:34:50 |
| 5 | Alvin Greene | 1200 | 2017-08-16 15:34:50 |
| 6 | Sophie Freeman | 1200 | 2017-08-16 15:34:50 |
| 8 | Donald D. Chamberlin | 2400 | 2017-08-16 15:35:33 |
| 9 | Raymond F. Boyce | 2400 | 2017-08-16 15:35:33 |
+-----------+----------------------+-----------+---------------------+
7 rows in set (0.00 sec)
Here is the current full student list to compare to the where clause result sets above.
SELECT studentID, FullName, sat_score, rcd_updated FROM student;
+-----------+------------------------+-----------+---------------------+
| studentID | FullName | sat_score | rcd_updated |
+-----------+------------------------+-----------+---------------------+
| 1 | Monique Davis | 400 | 2017-08-16 15:34:50 |
| 2 | Teri Gutierrez | 800 | 2017-08-16 15:34:50 |
| 3 | Spencer Pautier | 1000 | 2017-08-16 15:34:50 |
| 4 | Louis Ramsey | 1200 | 2017-08-16 15:34:50 |
| 5 | Alvin Greene | 1200 | 2017-08-16 15:34:50 |
| 6 | Sophie Freeman | 1200 | 2017-08-16 15:34:50 |
| 7 | Edgar Frank "Ted" Codd | 2400 | 2017-08-16 15:35:33 |
| 8 | Donald D. Chamberlin | 2400 | 2017-08-16 15:35:33 |
| 9 | Raymond F. Boyce | 2400 | 2017-08-16 15:35:33 |
+-----------+------------------------+-----------+---------------------+
9 rows in set (0.00 sec)