![]() Consequently, it converts the given expression into the specified data type. The CAST() operator takes an expression/column and a data type. For instance, you can convert a numeric string into an integer, string to double precision, string to boolean, etc. PostgreSQL provides a CAST operator that assists us in converting one data type to another. This is how the CAST Operator works in PostgreSQL. This is because the bike_number column contains alphanumeric values that cannot be converted into the DOUBLE PRECISION data type. You can see that Postgres generates an error “invalid input syntax”. This time we will try to convert the bike_number column into the DOUBLE PRECISION data type: SELECT CAST(bike_number AS DOUBLE PRECISION) FROM bike_details Let’s consider the same bike_details table: SELECT * FROM bike_details Trying to convert an expression that cannot be converted to the specified data type will generate an error. DOUBLE PRECISION.Įxample #5: Invalid Type Conversion in Postgres? The selected column has been converted into the desired data type i.e. Let’s execute the below statement to convert the TEXT data type to DOUBLE PRECISION data type: SELECT CAST(bike_price AS DOUBLE PRECISION) FROM bike_details The bike_price column has a TEXT data type. In our example database, we have created a bike_details table that contains following records: SELECT * FROM bike_details The data type of published_date column has been converted to the DATE type.Įxample #4: How to Use a CAST Operator to Convert a String Into a Double Type? Let’s convert it into DATE type using the CAST operator: SELECT CAST(published_date AS DATE) FROM article_details The published_date column has a text data type. Let’s execute the SELECT query to get the table’s details: SELECT * FROM article_details ![]() ![]() We have created a table named article_details in our database. The output shows that the data type of team_rating column has been changed to INTEGER data type.Įxample #3: How to Use CAST Operator For String to Date Type Conversion? Let’s convert it into INTEGER data type using the CAST operator: SELECT CAST(team_rating AS INTEGER) The result set shows that the team_rating column has a TEXT data type. Let’s run the SELECT statement to get the table’s details: SELECT * FROM team_details We have created a table named team_details. The output proves that the CAST operator takes a constant string and converts it into the desired data type, i.e., integer.Įxample #2: How to Use the CAST Operator to Table’s Column? Run the below statement to convert the given constant string to an integer: SELECT CAST ('572' AS INTEGER) The given expression will be converted into the targeted data type.Įxample #1: How to Use CAST Operator to Convert/Cast a String to Integer? While data_type represents a targeted data type. Here, exp represents an expression to be evaluated, such as a table’s column, an expression, or a constant. The below snippet illustrates the basic syntax of the CAST operator: CAST (exp AS data_type) How to Use the CAST Operator in PostgreSQL? Using practical examples, this post will explain how the CAST operator works in PostgreSQL. For this purpose, PostgreSQL provides a CAST operator that assists us in converting one data type to another. For instance, converting a numeric string into an int, a string to date, etc. One of the benefits that LPAD() has over the previous method is that we can prefix the result other characters – it doesn’t need to be a leading zero.While working with PostgreSQL, we may encounter a situation where we need to convert one data type into another. So we may have to do something like this: SELECT LPAD(CAST(7 AS varchar), 3, '0') The padding character also needs to be a string. Therefore, we need to convert the number to a string first. Note that this function requires that the number is passed as a string. We can alternatively use the LPAD() function to pad numbers with leading zeros: SELECT LPAD('7', 3, '0') Here’s an example to demonstrate this: SELECT But when the number is positive, no sign is included, and a space appears where the plus sign would have been. For example, when the number is negative, a minus sign is prefixed. The fm format modifier suppresses any leading and/or trailing padding that might be included in the result. The number of leading zeros are determined by the number of 0 format elements and the number of digits in the number: SELECT Here it is when compared to the 9 format element: SELECT When using the TO_CHAR() function, use the 0 format element to include leading and/or trailing zeros. The function converts the number to a string, using the (optional) format we specify.Īnother option is to use the LPAD() function to pad a number with leading zeros. In PostgreSQL, we can use the TO_CHAR() function to add leading zeros to a number.
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