So when we specify it to be cast to integer, the 'to be casted' object should comprise of numbers only. The reason is that 100ab comprises of both numbers and characters. We get a proper result set where 100 is returned as an integer and not a string.īut if we want to cast an alphanumeric text, say '100ab ' to integer, which is not possible. Like we discussed above, suppose we need to do some mathematical calculations on a number, which is actually stored in a varchar datatype column. If we write something like: SELECT '100'::integer We will understand few such DOs and DONTs with some simple examples. To use the CAST operator to type cast from datatype to another, we also need to ensure that the data can be converted to the target datatype or qualifies to be of the target datatype too. Just like other operations, CAST in PostgreSQL also has it's own DOs and DONTs. We can do it either writing: SELECT CAST(97 AS varchar) ĭifferent scenarios of CAST in PostgreSQL This means we need to convert an integer datatype to string datatype. Suppose we want the number 97 to be returned to us a String datatype. Instead of using the above syntax, we can also use the following condensed syntax: expression::type The target_type is the final datatype to which you want to convert the above expression to.The expression can be a constant or a table column or any expression that finally resolves to a value,.The syntax for using the CAST operator is: CAST ( expression AS target_type ) This can be done using the CAST operator. So, to add the numbers, we would need to cast them to integer once. In such case, the number/integer from such column will be returned as a varchar (or string). However, though the column stores numbers/integers, the datatype has been set as varchar by the database administrator. Suppose we need to add 2 numbers stored in 2 columns of a row/record in a table. Let's understand why do we need the casting technique (or briefly the CAST operator) in PostgreSQL with a very simple yet practical example. This article will illustrate the functions of CAST operator in PostgreSQL with hands-on examples. We can perform various cast operations in PostgreSQL for converting one datatype to another, such as the String datatype to the Integer datatype (or the Boolean datatype or datetime datatype) and vice versa. Cast is a technique in PostgreSQL with which we can convert a value of one datatype into another.

Pgadmin varchar