When you create a table in SQLite, you can also create a foreign key in order to establish a relationship with another table.
This article provides an example of creating a foreign key when creating a table in SQLite.
Continue readingAuthor: Ian
How to Enable Foreign Key Support in SQLite
In SQLite, foreign key constraints are not enforced unless foreign key support has been enabled.
Enabling foreign keys involves the following:
- Enable foreign keys when compiling SQLite.
- Enable foreign keys at runtime.
Restore an SQLite Database
This article explains how to restore an SQLite database from within the SQLite command line interface.
There are a few ways to restore a database from the SQLite CLI.
One way to do it is to simply attach a new database using the backup file (or a copy of it). Another way to restore a database is to use the .restore dot command to restore the database file to your chosen database within SQLite CLI.
How Group_Concat() Works in SQLite
SQLite has a group_concat() function that allows you to concatenate multiple results returned for a column into one.
This is sometimes referred to as “string aggregation”.
For example, when querying a database, instead of having each column’s value output in a new row, you can use group_concat() to have them output as a comma separated list.
How Substr() Works in SQLite
The SQLite substr() function allows you to return a substring from a string, based on a given starting location within the string.
It requires two arguments, and accepts a third optional argument.
Continue readingHow Round() Works in SQLite
In SQLite, the round() function allows you to round numbers up or down to a given decimal place.
It returns a floating-point value from the first argument, with the number of decimal places that you specify in the (optional) second argument.
If you don’t provide the second argument, it’s assumed to be 0.
Continue readingHow SQLite Lower() Works
The SQLite lower() function allows you to convert a string to lowercase characters.
More precisely, it returns a copy of its argument, with all ASCII characters converted to lowercase.
Continue readingHow SQLite Upper() Works
The SQLite upper() function allows you to convert a string to uppercase characters.
More precisely, it returns a copy of its argument, with all ASCII characters converted to uppercase.
Continue readingHow SQLite Nullif() Works
The SQLite nullif() function is a handy function that allows you to treat certain values as NULL when required.
It’s not to be confused with the ifnull() function, which does the opposite – enables you to treat NULL values as something else.
The nullif() function accepts two arguments, and returns its first argument if the arguments are different and NULL if the arguments are the same.
How SQLite Random() Works
The SQLite random() function returns a pseudo-random integer between -9223372036854775808 and +9223372036854775807.
A pseudo-random number is a number that appears to be random, but is not truely random. A pseudo-random number is not truely random because its value was generated by a known seed. However, a pseudo-random number will appear to be random if the user has no knowledge of the seed or algorithm that created it.
Therefore, pseudo-random numbers are often considered good enough for many applications.
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