Concatenate Array Elements into a String in PostgreSQL

You may be aware that PostgreSQL has a couple of functions that allow us to concatenate strings. In particular, the concat() function allows us to concatenate multiple strings into one string, and the concat_ws() function allows us to do the same, but to also specify a separator for the concatenated strings.

But did you know that we have the ability to pass an array to these functions?

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Using the VARIADIC Keyword with the FORMAT() Function in PostgreSQL

When we use the format() function in PostgreSQL, we can pass any number of strings to insert into the resulting formatted string in positions that are specified in the first argument. When we do this, we might typically pass the strings as separate arguments. But this isn’t the only way to do it.

We have the option of passing the strings as array elements. That is, we can pass an array to the function, and have it extract each array element as though it’s a separate argument to insert into the formatted string.

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How to Select an Element from an Array in PostgreSQL

PostgreSQL provides us with the ability to create arrays, extract element values from them, and more. When it comes to selecting values, there’s a special syntax that we must use in order to get the exact element that we want to select.

Basically, the syntax involves the array or column name, followed by a pair of square brackets with the subscript of the element that we want to select.

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2 Ways to Insert an Array into a Table in PostgreSQL

PostgreSQL allows us to create columns that store arrays. That is, we can define the column as an array column so that we can insert arrays into the column. This enables us to work with the arrays in the columns without it being confused with plain text.

We have a couple of options for inserting arrays into columns. One is to use an array literal. Another is to use an array constructor. Examples of each of these options are below.

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How to Create an Array Column in PostgreSQL

PostgreSQL allows us to create arrays and store them in a database column. When we do this, we can use various array related tools to retrieve data from such arrays, as well as manipulate the data within them.

We do need to define the column as an array column though. If we don’t do this, we will likely run into trouble when we want to retrieve data from the array. For example, we can’t just store an array as the text type and then expect to be able to use subscripts to refer to its individual elements.

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