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| + | ====== List Users ====== | ||
| + | <code sql> | ||
| + | SELECT user FROM mysql.user; | ||
| + | </ | ||
| + | |||
| + | ====== Reset Passwords ====== | ||
| + | |||
| + | Sets the password '' | ||
| + | |||
| + | <code sql> | ||
| + | UPDATE mysql.user SET password=PASSWORD(' | ||
| + | </ | ||
| + | |||
| + | ====== List the Size of Databases ====== | ||
| + | |||
| + | <code sql> | ||
| + | SELECT table_schema " | ||
| + | </ | ||
| + | |||
| + | ====== Select Random Records ====== | ||
| + | |||
| + | The following query, selects one random entry from the table '' | ||
| + | |||
| + | <code sql> | ||
| + | SELECT * FROM table ORDER BY RAND() | ||
| + | </ | ||
| + | |||
| + | ====== Select Using RegExp ====== | ||
| + | |||
| + | This query will select '' | ||
| + | |||
| + | <code sql> | ||
| + | SELECT lastname, firstname FROM employees WHERE lastname REGEXP | ||
| + | </ | ||
| + | |||
| + | ====== Comma-separated Values ====== | ||
| + | |||
| + | A structurally simple format is the '' | ||
| + | |||
| + | ===== Export ===== | ||
| + | |||
| + | This line exports data from the table '' | ||
| + | |||
| + | <code sql> | ||
| + | SELECT * FROM account INTO OUTFILE '/ | ||
| + | </ | ||
| + | |||
| + | ===== Import ===== | ||
| + | |||
| + | Imports are preformed symmetrically, | ||
| + | <code sql> | ||
| + | LOAD DATA INFILE '/ | ||
| + | </ | ||
| + | |||
| + | ====== Dump and Restore a Database ====== | ||
| + | |||
| + | To dump a database to a file, issue: | ||
| + | <code bash> | ||
| + | mysqldump -u root -p database > database.sql | ||
| + | </ | ||
| + | |||
| + | to restore a database from a file, issue: | ||
| + | <code bash> | ||
| + | mysqldump -u root -p database < database.sql | ||
| + | </ | ||
| + | |||
| + | ====== Sum-Up Columns in MySQL Table ====== | ||
| + | |||
| + | Given the following table: | ||
| + | |||
| + | ^ '' | ||
| + | | '' | ||
| + | | '' | ||
| + | | '' | ||
| + | | '' | ||
| + | | '' | ||
| + | | '' | ||
| + | |||
| + | we want to find out the total score for '' | ||
| + | |||
| + | <code sql> | ||
| + | SELECT Name, | ||
| + | </ | ||
| + | |||
| + | which will return the following table: | ||
| + | |||
| + | ^ '' | ||
| + | | '' | ||
| + | |||
| + | The same can be done if the scores are distributed on multiple columns: | ||
| + | |||
| + | ^ '' | ||
| + | | '' | ||
| + | |||
| + | To find out the total, summative score for '' | ||
| + | |||
| + | <code sql> | ||
| + | SELECT Name, | ||
| + | </ | ||
| + | |||
| + | which will return the table: | ||
| + | |||
| + | ^ '' | ||
| + | | '' | ||
| + | |||
| + | ====== Empty a Database Without Dropping ====== | ||
| + | |||
| + | To empty the database '' | ||
| + | |||
| + | <code sql> | ||
| + | SELECT CONCAT(' | ||
| + | </ | ||
| + | |||
| + | ====== Repair MySQL Tables ====== | ||
| + | |||
| + | <code bash> | ||
| + | mysql -Be " | ||
| + | </ | ||
| + | |||
| + | or | ||
| + | |||
| + | <code bash> | ||
| + | mysqlcheck --auto-repair -A | ||
| + | </ | ||
| + | |||
| + | ====== Reset Root Password ====== | ||
| + | |||
| + | First, stop MySQL using: | ||
| + | <code bash> | ||
| + | / | ||
| + | </ | ||
| + | |||
| + | Now we run MySQL by omitting to read the grant tables: | ||
| + | <code bash> | ||
| + | mysqld --skip-grant-tables | ||
| + | </ | ||
| + | |||
| + | And we log-in as '' | ||
| + | <code bash> | ||
| + | mysql -u root | ||
| + | </ | ||
| + | |||
| + | Then we run a query to replace the root password: | ||
| + | <code sql> | ||
| + | FLUSH PRIVILEGES; | ||
| + | UPDATE mysql.user SET Password=PASSWORD(' | ||
| + | FLUSH PRIVILEGES; | ||
| + | exit | ||
| + | </ | ||
| + | |||
| + | And after that we restart MySQL: | ||
| + | <code bash> | ||
| + | / | ||
| + | </ | ||
| + | |||
| + | ====== Import Multiple SQL Files ====== | ||
| + | |||
| + | In a directory containing '' | ||
| + | <code bash> | ||
| + | ls -1 *.sql | awk '{ print " | ||
| + | </ | ||
| + | |||
| + | where: | ||
| + | * '' | ||
| + | * '' | ||
| + | * '' | ||
| + | |||
| + | ====== Drop all Tables in Database ====== | ||
| + | |||
| + | This can be accomplished with: | ||
| + | |||
| + | <code bash> | ||
| + | mysql -u USER --password=PASSWORD -Nse 'SHOW TABLES' | ||
| + | </ | ||
| + | |||
| + | where: | ||
| + | |||
| + | * '' | ||
| + | * '' | ||
| + | * '' | ||
| + | |||
| + | ====== Truncate all Tables in Database ====== | ||
| + | |||
| + | This can be done with: | ||
| + | <code bash> | ||
| + | mysql -u USER --password=PASSWORD -Nse 'show tables' | ||
| + | </ | ||
| + | |||
| + | where: | ||
| + | |||
| + | * '' | ||
| + | * '' | ||
| + | * '' | ||
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