Ian – Page 137

Fix “Cannot drop a default constraint by DROP DEFAULT statement. Use ALTER TABLE to drop a constraint default.” in SQL Server

September 5, 2024February 19, 2023 by Ian

If you’re getting an error that reads something like “Cannot drop a default constraint by DROP DEFAULT statement. Use ALTER TABLE to drop a constraint default“, it’s because you’re trying to use DROP DEFAULT to drop a DEFAULT constraint.

The DROP DEFAULT statement has been flagged for deletion from SQL Server, and Microsoft recommends that we use the ALTER TABLE statement to drop DEFAULT constraints.

Therefore, to fix this issue, use the ALTER TABLE statement to drop the DEFAULT constraint.

What is DQL?

February 21, 2023February 18, 2023 by Ian

We often hear terms like DDL, DML, DQL, TCL, and DCL when using relational database management systems (RDBMSs). But what exactly are they?

In this article we’ll look at what DQL stands for, and what it does.

Fix “ERR wrong number of arguments for ‘hstrlen’ command” in Redis

February 18, 2023 by Ian

If you’re getting an error that reads “ERR wrong number of arguments for ‘hstrlen’ command“, it’s because you’re passing the wrong number of arguments when using the HSTRLEN command.

The HSTRLEN command requires two arguments (at the time of writing). These are the name of the key and the name of the field.

If you’re getting this error, check the number of arguments that you’re passing and adjust if required.

What is DML?

February 21, 2023February 17, 2023 by Ian

We often hear terms like DDL, DML, DQL, and DCL when using relational database management systems (RDBMSs). But what exactly are they?

In this article we’ll look at what DML stands for, and what it does.

Fix “ERROR 1054 (42S22): Unknown column ‘…’ in ‘on clause'” in MySQL

February 17, 2023 by Ian

If you’re getting an error in MySQL that reads something like “ERROR 1054 (42S22): Unknown column ‘c.DogName’ in ‘on clause”“, here are three likely causes:

The column doesn’t exist.
You’re trying to reference an aliased column by its column name.
Or it could be the other way around. You could be referencing the column with an alias that was never declared.

What is DDL?

February 21, 2023February 16, 2023 by Ian

We often encounter terms like DDL, DML, DQL, DCL, and TCL when using relational database management systems (RDBMSs). But what do they mean?

In this article we’ll look at what DDL stands for and what it does.

MySQL Date & Time Functions (Full List)

February 15, 2023 by Ian

The following is a list of date and time functions available in MySQL. Click on each function name to see an explanation of the function, its syntax, and examples.

How CONVERT() Works in MySQL

February 14, 2023 by Ian

In MySQL, CONVERT() is a built in function that converts a value to another data type. It takes a value of one type and returns a value of the specified type.

We provide the value as an argument when we call the function, as well as the type that we want it converted to.

The CONVERT() function is similar to the CAST() function, which also converts between data types.

How to Specify the Data Type when Creating a Sequence in SQL Server

February 13, 2023 by Ian

When creating a sequence object in SQL Server, the default data type is bigint. However, we can change this so that the sequence uses a data type of our choosing, as long as it’s an integer type (see below for accepted data types).

We can set the data type of a sequence by using the AS argument when defining the sequence.

Fix “WRONGTYPE Operation against a key holding the wrong kind of value” when using ZSCORE in Redis

February 12, 2023 by Ian

If you get an error that reads “WRONGTYPE Operation against a key holding the wrong kind of value” when using the ZSCORE command in Redis, it’s because you’re passing a key with the wrong data type.

To fix this issue, make sure that you pass a sorted set to the ZSCORE command.