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.
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.
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:
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.
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.
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.
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.
In MySQL, ROW_COUNT() is a built-in function that returns the number of rows updated, inserted, or deleted by the preceding statement.
The value returned by ROW_COUNT() is often the same as the row count that the mysql client displays following statement execution, as well as the value from the mysql_affected_rows() C API function.
The SQLite changes() function returns the number of database rows that were changed, inserted or deleted by the most recently completed INSERT, DELETE, or UPDATE statement, exclusive of statements in lower-level triggers.
Basically, it allows us to see how many rows are affected when we run any of those statements.