Copy an Existing Data Directory With this method, any MySQL accounts or user data present in the data directory are carried over to the new data directory. 1. Stop the existing MySQL instance using the data directory. This must be a clean shutdown
Counting Rows Databases are often used to answer the question, “How often does a certain type of data occur in a table?” For example, you might want to know how many pets you have, or how many pets each owner has, or you might want to perform various kinds of
Create a mysql User and Group If your system does not already have a user and group for mysqld to run as, you may need to create one. The following commands add the mysql group and the mysql user. You might want to call the user and group something else instead of mysql. If so, substitute the app...
Create a New Data Directory With this method, the data directory will be in the same state as when you first install MySQL. It will have the default set of MySQL accounts and no user data. On Unix, initialize the data directory by running mysql_...
Creating a Table Creating the database is the easy part, but at this point it is empty, as SHOW TABLES tells you: mysql SHOW TABLES; Empty set (0.00 sec) The harder part is deciding what the structure of your database should be: what tables you need and what columns should be in each of them. ...
Creating an Option File If you need to specify startup options when you run the server, you can indicate them on the command line or place them in an option file. For options that are used every time the server starts, you may find it most conven...
Customizing the PATH for MySQL Tools To make it easier to invoke MySQL programs, you can add the path name of the MySQL bin directory to your Windows system PATH environment variable: • On the Windows desktop, right-click the My Computer icon, and select Properties. • Next select the Advanced ta...
Data types. These data type changes have been implemented: • MySQL now permits fractional seconds for TIME, DATETIME, and TIMESTAMP values, with up to microseconds (6 digits) precision. See Section 11.3.6, “Fractional Seconds in Time Values”. • ...
Date Calculations MySQL provides several functions that you can use to perform calculations on dates, for example, to calculate ages or extract parts of dates. To determine how many years old each of your pets is, use the TIMESTAMPDIFF() [1244] function. Its arguments are the unit in which you w...
DDL for Partitioned Tables The mechanism used for DDL operations on partitioned tables is somewhat different from the online DDL discussed throughout this section. The partitioning clauses of the ALTER TABLE statement are only allowed in conjunction with ALGORITHM=DEFAULT and LOCK=DEFAULT. Althou...
