In MySQL we can use the SHOW BINARY LOGS statement to return a list of binary log files on the server.
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An Overview of SHOW COLLATION in MySQL
In MySQL we can use the SHOW COLLATION statement to return all collations supported by the server. By default it returns all available collations, but we can filter the output down to just those collations that we’re interested in.
An Overview of the SHOW CHARACTER SET Statement in MySQL
In MySQL we can use the SHOW CHARACTER SET statement to return all available character sets. We can also use it to narrow the output down to just those we’re interested in.
A Quick Intro to SHOW INDEX in MySQL
In MySQL we can use the SHOW INDEX statement to return information about the indexes on a table.
We specify which table to show indexes from, and we can optionally specify which database. We can also use a WHERE clause to filter by various criteria.
We can run it against any table where we have some privilege for any column in the table.
Continue readingA Quick Overview of the ‘show_gipk_in_create_table_and_information_schema’ System Variable in MySQL
Depending on our configuration, if we create a table without a primary key column, MySQL will automatically create one behind the scenes. This is called a generated invisible primary key (GIPK).
We can normally use statements such as SHOW CREATE TABLE, SHOW COLUMNS, SHOW INDEX or even check the information schema to see if a table has a GIPK.
But this depends on the setting of our show_gipk_in_create_table_and_information_schema system variable.
This variable can be set to ON or OFF. When set to ON, we will see GIPKs in the output of the aforementioned statements. When set to OFF, we won’t see any GIPKs.
Understanding MySQL’s ‘sql_generate_invisible_primary_key’ System Variable
One of the more recent additions to MySQL’s list of system variables is the sql_generate_invisible_primary_key variable. This variable was introduced in MySQL 8.0.30 along with the introduction of generated invisible primary keys (GIPKs).
The purpose of this variable is to allow us to specify whether or not the system will generate a GIPK when we omit a primary key from a table’s definition when creating the table.
By default the sql_generate_invisible_primary_key is set to OFF, which basically means that GIPKs are disabled by default. But we can change this to ON in order to enable GIPKs.
What is a Generated Invisible Primary Key (GIPK) in MySQL?
While primary keys are generally considered a necessity when it comes to relational databases, they’re usually included in the SQL code that creates the database table.
MySQL 8.0.30 introduced generated invisible primary keys which provide an alternative to explicitly specifying a primary key for a table.
A generated invisible primary key (GIPK) is a primary key that’s created implicitly by the MySQL server. If we create a table without an explicit primary key, the MySQL server automatically creates a generated invisible primary key for us (assuming it’s an InnoDB table and that GIPKs are enabled).
Continue readingQuick Intro to SHOW CREATE DATABASE in MySQL
MySQL has a SHOW CREATE DATABASE statement that shows the CREATE DATABASE statement that would be used to recreate the database.
We can use the SHOW CREATE DATABASE statement to create an identical database on another server, or to create a similar database on the same server (while changing the name).
We can alternatively use SHOW CREATE SCHEMA to do the same thing (SHOW CREATE SCHEMA is a synonym for SHOW CREATE DATABASE).
What is a Composite Primary Key?
Primary keys are a crucial part of relational database management systems (RDBMSs). Most of the time we create a primary key constraint against a single column that is the unique identifier for the table.
But we can also create primary key constraints against more than one column. When we do this, we call it a composite primary key.
Composite keys can be handy when we don’t have a single column that contains unique values, but multiple columns can be combined to create a unique value.
Continue readingA Quick Overview of the SHOW CREATE TABLE Statement in MySQL
In MySQL, we can use the SHOW CREATE TABLE statement to produce a CREATE TABLE statement from an existing table.
This enables us to generate a script that we can use to recreate the table on another database, or on the same database at a later date. Or we could use it to create another similar table. We would need to modify the code accordingly when doing this, but it could give us a good starting point.
We can also use SHOW CREATE TABLE for a quick way to take a look at the table’s structure, and check for things like data types, primary keys, foreign keys, etc.