If you’re getting a PostgreSQL error that reads “searching for elements in multidimensional arrays is not supported“, it’s probably because you’re trying to perform an operation against a multi dimensional array when that operation only supports one dimensional arrays.
To fix this issue, perform the operation against a one dimensional array instead. You may be able to do this by applying the unnest() function against the multi dimensional array.
In PostgreSQL, we have many ways to retrieve data from arrays. One way is to specifically reference its subscript or a range of subscripts. Another way is to search through the array’s contents for the value we want.
By doing a search, I mean we could do things like filter the query with a WHERE clause, so that we only return rows that contain an array that has an element with a certain value.
If you’re getting an error that reads “could not determine polymorphic type because input has type unknown” when using the array_shuffle() function in PostgreSQL, it’s probably because your argument is of the wrong type.
The array_shuffle() function requires an array as its argument. Passing a non-array value will result in an error. The actual error can vary, depending on the argument you pass, but either way, the error is usually due to a non-array argument being passed.
To fix this error, be sure to pass an array as the argument when calling the array_shuffle() function.
If you’re getting an error that reads “multidimensional arrays must have array expressions with matching dimensions” it’s probably because you’re trying to create a multi-dimensional array where the inner arrays at the same level have different dimensions.
Multidimensional arrays must be rectangular. To fix this issue, make sure all arrays at the same level have the same dimensions.
Continue readingIn PostgreSQL, the array_length() function returns the length of the specified array dimension.
We pass the array as the first argument, and the dimension as the second.
Continue readingPostgreSQL has a datestyle variable that specifies the display format for date and time values, as well as the rules for interpreting ambiguous date input values.
We can set the date/time style with the SET datestyle command, the DateStyle parameter in the postgresql.conf configuration file, or the PGDATESTYLE environment variable on the server or client.
Below is an example of using the SET datestyle command to change the datestyle for the current session.
If you’re getting a PostgreSQL error that reads something like “cannot subscript type text because it does not support subscripting” when selecting data from a database, it’s probably because you’re trying to perform some sort of array operation against a non array value.
The above error specifically mentions text data but we could get the same error when using a different data type, like an integer, character varying, etc.
To fix this issue, be sure to run the array operations against actual arrays. If working with non array data, then don’t use array operations against that data.
Continue readingIn PostgreSQL we can use the ARRAY constructor to create an array. When we do this, we provide the array elements as a comma separated list, enclosed in square brackets. Postgres then works out the data type based on the array elements.
But what if we want to create an empty array?
Creating an empty array can cause issues if we don’t explicitly specify the type. We need to specify the type. Below is an example of creating an empty array in PostgreSQL using the ARRAY constructor.
In MySQL we can use the ALTER EVENT statement to make changes to existing scheduled events, including changing the name of the event.
If you’re getting a PostgreSQL error that reads something like “function generate_subscripts(text[], integer, integer) does not exist“, it’s probably because your third argument is of the wrong type when using the generate_subscripts() function.
The above error specifically implies that an integer was passed as the third argument, but it must be a boolean value.
The third argument of the generate_subscripts() function is optional, but if passed, it must be a boolean expression.
To fix this error, either pass a boolean value as the third argument, or eliminate the third argument altogether.
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