Simply group on both of the columns. Note: the older ANSI standard is to have all non-aggregated columns in the GROUP BY but this has changed with the idea of “functional dependency”: In relational database theory, a functional dependency is a constraint between two sets of attributes in a relation from a database. In other words, … Read more
One-to-one: Use a foreign key to the referenced table: You must also put a unique constraint on the foreign key column (addess.student_id) to prevent multiple rows in the child table (address) from relating to the same row in the referenced table (student). One-to-many: Use a foreign key on the many side of the relationship linking back … Read more
There are mainly three types of variables in MySQL: User-defined variables (prefixed with @):You can access any user-defined variable without declaring it or initializing it. If you refer to a variable that has not been initialized, it has a value of NULL and a type of string.SELECT @var_any_var_name You can initialize a variable using SET or SELECT statement:SET @start = 1, @finish = … Read more
May be this will help you.
Use the following query: The RENAME function is used in Oracle databases. @lad2025 mentions it below, but I thought it’d be nice to add what he said. Thank you @lad2025! You can use the RENAME COLUMN in MySQL 8.0 to rename any column you need renamed. ALTER TABLE Syntax: RENAME COLUMN: Can change a column name but not its definition. More … Read more
Should you instead be setting the identity insert to on within the stored procedure? It looks like you’re setting it to on only when changing the stored procedure, not when actually calling it. Try:
On Mac OS X v10.6 (Snow Leopard), starting MySQL gives the following error: The server quit without updating PID file File my.cnf log-error=/var/log/mysqld.log pid-file=/var/run/mysqld/mysqld.pid
Looks like the mysql server is not started. Look to the official documentation of MySQL how you can start a service under windows. Install the server as a service using this command: C:> “C:\Program Files\MySQL\MySQL Server 5.5\bin\mysqld” –install
Yes, something like this: As other answers have pointed out, MySQL also has the IF() function to do this using less verbose syntax. I generally try to avoid this because it is a MySQL-specific extension to SQL that isn’t generally supported elsewhere. CASE is standard SQL and is much more portable across different database engines, and I prefer to … Read more
Looks like the mysql server is not started. Look to the official documentation of MySQL how you can start a service under windows. Install the server as a service using this command: C:> “C:\Program Files\MySQL\MySQL Server 5.5\bin\mysqld” –install