Most of the major DBMSs provide us with a way to find a string within a string using SQL. By this, I mean use a SQL query to find the position of a substring within a string.
There are several SQL functions that allow us to do this, including INSTR(), LOCATE(), POSITION(), and CHARINDEX(). The function you use will depend on your DBMS, and possibly whether or not you need to specify a starting position.
If you’re trying to back up the transaction logs in a SQL Server or SQL Edge database, but you get an error that states BACKUP LOG cannot be performed because there is no current database backup, you’ll need to perform at least one full backup of the database before you attempt to back up the transaction logs.
Many RDBMSs have an INSTR() function that enables us to find a substring within a string. Some (such as MySQL and MariaDB) also have a LOCATE() function and a POSITION() function (also supported by PostgreSQL), that do a similar thing.
SQL Server doesn’t have an INSTR() function. Nor does it have a LOCATE() or POSITION() function. But it does have the CHARINDEX() function that does the same thing.
SQL Server also has the PATINDEX() function, which does a similar job to CHARINDEX().
If you get an error that reads The statement BACKUP LOG is not allowed while the recovery model is SIMPLE when trying to back up a database in SQL Server or Azure SQL Edge, it’s because you’re trying to back up the transaction logs on a database that uses the simple recovery model.
To fix this, change the recovery model to either full or bulk logging.
In SQL Server, the TODATETIMEOFFSET() function was specifically designed to return a datetimeoffset value from a datetime2 value.
Given the fact that the datetime2 data type doesn’t actually support time zone offsets, and datetimeoffset must contain the offset, the TODATETIMEOFFSET() function allows you to specify a time zone offset to use.
This article provides some examples to demonstrate.
Most of the major RDBMSs provide several options for concatenating two or more strings.
CONCAT() function, which concatenates its arguments.CONCAT_WS() that allows you to specify a separator that separates the concatenated strings.Below are examples of each method.