add show databases document
@@ -8,20 +8,91 @@ Shows the list of databases that exist on the instance.
## Syntax
```
-SHOW DATABASES
+SHOW DATABASES [LIKE expr | WHERE expr]
```
## Examples
-
```
mysql> SHOW DATABASES;
+----------+
-| name |
+| Database |
+----------+
| default |
| for_test |
| local |
+| ss |
+| ss1 |
+| ss2 |
+| ss3 |
| system |
| test |
+----------+
+9 rows in set (0.00 sec)
+```
+
+Showing the databases with database `"ss"`:
+```
+mysql> SHOW DATABASES WHERE Database = 'ss';
++----------+
+| Database |
++----------+
+| ss |
++----------+
+1 row in set (0.01 sec)
+```
+
+Showing the databases begin with `"ss"`:
+```
+mysql> SHOW DATABASES Like 'ss%';
++----------+
+| Database |
++----------+
+| ss |
+| ss1 |
+| ss2 |
+| ss3 |
++----------+
+4 rows in set (0.01 sec)
+```
+
+Showing the databases begin with `"ss"` with where:
+```
+mysql> SHOW DATABASES WHERE Database Like 'ss%';
++----------+
+| Database |
++----------+
+| ss |
+| ss1 |
+| ss2 |
+| ss3 |
++----------+
+4 rows in set (0.01 sec)
+```
+
+Showing the databases like substring expr:
+```
+mysql> SHOW DATABASES Like SUBSTRING('ss%' FROM 1 FOR 3);
++----------+
+| Database |
++----------+
+| ss |
+| ss1 |
+| ss2 |
+| ss3 |
++----------+
+4 rows in set (0.01 sec)
+```
+
+Showing the databases like substring expr with where:
+```
+mysql> SHOW DATABASES WHERE Database Like SUBSTRING('ss%' FROM 1 FOR 3);
++----------+
+| Database |
++----------+
+| ss |
+| ss1 |
+| ss2 |
+| ss3 |
++----------+
+4 rows in set (0.01 sec)
```
