The SQLite json_object() function returns a well-formed JSON object based on its arguments.
The function accepts zero or more pairs of arguments and returns a well-formed JSON object based on those arguments.
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SQLite JSON()
In SQLite, the json() function converts raw text that looks like JSON into actual JSON.
We pass a JSON string as an argument when we call the function. The json() function then checks that the argument is a valid JSON string and returns a minified version of that JSON string. If the argument is not a well-formed JSON string, then an error is thrown.
However, the json() function was not designed to test whether or not a value is valid JSON. To do that, use the json_valid() function instead.
PostgreSQL SHOW TABLES Equivalent (psql)
MySQL and MariaDB have a SHOW TABLES statement, which outputs a list of tables and views in a database. PostgreSQL doesn’t have a SHOW TABLES statement, but it does have a command that produces a similar result.
In Postgres, you can use the \dt command to show a list of tables. This is a psql command (psql is the interactive terminal for PostgreSQL).
SQLite SUBSTRING() Explained
In SQLite, substring() is an alias for substr().
It returns a substring from a string, based on a given starting location within the string. Two arguments are required, and a third optional argument is accepted.
The substring() naming was introduced in SQLite 3.34.0, which was released on 1st December 2020. The reason that the substring() syntax was introduced was for compatibility with SQL Server.
SQLite Renames PRINTF() to FORMAT()
SQLite has introduced the FORMAT() function, which can be used to format strings.
More precisely, it has actually just renamed its SQL PRINTF() function to FORMAT(). The reason is for better compatibility with other DBMSs. The original PRINTF() name is retained as an alias for backwards compatibility.
The FORMAT() function (or its naming) was introduced in SQLite 3.38.0, which was released on 22 February 2022.
SQLite SHOW TABLES Equivalent
SQLite doesn’t have a SHOW TABLES statement like MySQL and MariaDB have, but it does have a similar command.
In SQLite, you can use the .tables command to show a list of tables. You can alternatively use the table_list pragma to do the job.
SQLite Introduces the UNIXEPOCH() Function
SQLite 3.38.0 was released on 2nd February 2022. With it came some enhancement to the date and time functions.
One of those enhancements is the addition of the UNIXEPOCH() function. This function returns a unix timestamp. That is, the number of seconds since 1970-01-01 00:00:00 UTC.
SQLite DATEADD() Equivalent
SQLite doesn’t have a DATEADD() function like SQL Server (or an ADDDATE() or ADD_DATE() function like in some other DBMSs), but it does have the DATE() function that can make additions to a date value.
SQLite also has a DATETIME() function that can make additions to a datetime value (as well as a TIME() function for time values).
VALUES Clause in SQL Server
In SQL Server, VALUES is a table value constructor that specifies a set of row value expressions to be constructed into a table.
The VALUES clause is often used with INSERT statements to insert data, but it can also be used as a derived table in either the USING clause of the MERGE statement or the FROM clause.