In PostgreSQL we have the ability to create variable-length multidimensional arrays and define columns as array types.
Here’s a quick overview of PostgreSQL arrays.
Continue readingAuthor: Ian
How to Enable/Disable a Scheduled Event in MySQL
When we create a scheduled event in MySQL, it’s enabled by default. But we can change this.
We can create an event in disabled status, then enable it later. Or we can do the opposite – create it as an enabled event and then disable it later.
Continue readingFix Error “function generate_subscripts(integer, integer) does not exist” in PostgreSQL
If you’re getting a PostgreSQL error that reads “function generate_subscripts(integer, integer) does not exist“, it’s probably because your first argument is not an array. This specific error message implies that the first argument is an integer, but we’d get a similar error when passing a numeric argument.
The first argument for this function must be an array.
To fix this error, be sure that your first argument to generate_subscripts() is an array.
Fix “invalid input syntax for type integer…” When Using array_sample() in PostgreSQL
If you’re getting an error that reads “invalid input syntax for type integer…” when using the array_sample() function in PostgreSQL, it’s probably because your second argument is not an integer.
The second argument for this function must be an integer.
To fix this error, be sure that your second argument to array_sample() is an integer.
A Quick Overview of ARRAY_AGG() in PostgreSQL
PostgreSQL has an aggregate function called array_agg() that allows us to generate an array from the result set of a query.
The function accepts an argument which is used to generate the array. This argument is typically the column that we want to use in order to populate the array.
Continue reading5 Ways to Enable Vertical Output in psql
When we use psql to write SQL queries in PostgreSQL, we’ll usually see the results presented as a table, with columns displayed vertically and rows running horizontally. But it is possible to change this so that the columns are displayed horizontally and the rows run vertically.
This can be useful for when the number of columns causes the results to be wider than our psql display, and may cause the rows to wrap to the next line.
Here are five ways we can change the display to vertical output, otherwise known as expanded display.
Continue readingHow to “Unhide” a GIPK in MySQL
In MySQL, GIPKs are invisible by definition. GIPK stands for generated invisible primary key, and it’s basically an invisible column automatically created by MySQL with a primary key constraint.
However, just because GIPKs are automatically created invisible, it doesn’t mean that we can’t “unhide” them – or make them visible.
We can make a GIPK visible just as we would make any other invisible column visible – use the ALTER TABLE statement to set it to VISIBLE.
Understanding the ARRAY Constructor in PostgreSQL
In PostgreSQL we can create arrays with the ARRAY constructor. An array constructor is an expression that builds an array value using values for its member elements.
How to Check the Current datestyle Setting in PostgreSQL
PostgreSQL has a datestyle setting that specifies the display format for date and time values, as well as the rules for interpreting ambiguous date input values.Â
We can check the current value of our datestyle setting by running SHOW datestyle.
An Overview of the GENERATE_SUBSCRIPTS() Function in PostgreSQL
PostgreSQL has a generate_subscripts() function that generates a series comprising the valid subscripts of a given array.
We pass the array to the function, along with the dimension that we want to use. We also have the option of returning the series in reverse order.
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