Postgresql cast integer to string12/6/2023 ![]() ![]() ![]() In this tutorial, you have learned how to use the CAST() and TO_CHAR() functions to convert a date to a string in SQL. The following example uses the TO_CHAR() function to format the current date using the YYYY-MM-DD format in Oracle: SELECT The following illustrates the syntax of the TO_CHAR() function: TO_CHAR(value, format) You can use the TO_CHAR() function to format a date as a string. The DB2, Oracle, MySQL and PostgreSQL provide a function named TO_CHAR() that has a similar feature to the CAST function. Convert date to string using TO_CHAR() function The following statement returns the current date and time as a date and as a string: SELECT CURRENT_TIMESTAMP 'date',ĬAST( CURRENT_TIMESTAMP AS VARCHAR) 'date as a string' Įven though CAST() is a standard-SQL function, not so many database systems support it. The CAST() function returns a string that represents the date. The string can be any character string data type such as VARCHAR or TEXT.Return the base 10 logarithms of a numeric value. Return the natural logarithm of a numeric value. The date can be a literal or an expression that evaluates to a DATE value. Round a number down to the nearest integer, which is less than or equal to the number.To convert a date to a string, you use the CAST() function as follows: CAST(date AS string)Ĭode language: SQL (Structured Query Language) ( sql ) Convert date to string using CAST() function If other exceptions are even remotely common, it pays to filter invalid strings without raising an exception.Summary: in this tutorial, you will learn various functions to convert a date to a string in SQL. Python int values can be converted to PostgreSQL smallint, integer, bigint, or numeric, according to their numeric value. If empty strings are common it makes sense to catch that separately. The following illustrates the syntax of type CAST: CAST ( expression AS targettype ) Code language: SQL (Structured Query Language) (sql) In this syntax: First, specify an expression that can be a constant, a table column, an expression that evaluates to a value. Regular expressions are also expensive - even if on a much smaller scale. Syntax The syntax of PostgreSQL TONUMBER () function is as follows: TONUMBER (string, format) Arguments The TONUMBER () function requires two arguments. PostgreSQL provides you with the CAST operator that allows you to do this. The function can easily be adapted for any data type conversion.Įntering an exception block is expensive. Note that the simple regular expression does not catch all violations (like "out of range"). 14 Answers Sorted by: 200 I was just wrestling with a similar problem myself, but didnt want the overhead of a function. ![]() Find not-integer values in a string column.This returns 0 for an empty string or any other invalid input. ![]() RETURN 0 - or null ? - other invalid input, like "out of range" Convert seconds to days, hours and minutes. IF $1 = '' THEN - special case for empty string IF that is commonĮLSIF $1 !~ '^*\d+$' THEN - obviously invalid (would also catch '') Includes epoch explanation and conversion syntax in various programming languages. Also, the question asks to convert empty strings ( '') to 0, but not other "invalid input syntax" or "out of range" input: CREATE OR REPLACE FUNCTION convert_to_int(text) I came up with the following query: SELECT myfield::integer FROM mytable WHERE myfield E'\\d+' Postgres shortcuts its conditionals, so you shouldn't get any non-integers hitting your ::integer cast. It works similar to the simpler solutions, except will give 0 when the value to convert is non-digit characters only, such as "bad": db=> select CAST((COALESCE(NULLIF(REGEXP_REPLACE('no longer bad!', '+', '', 'g'), ''), '0')) AS INTEGER) 14 Answers Sorted by: 200 I was just wrestling with a similar problem myself, but didn't want the overhead of a function. To address Chris Cogdon's concern with the solution not giving 0 for all cases, including a case such as "bad" (no digit characters at all), I made this adjusted statement: CAST((COALESCE(NULLIF(REGEXP_REPLACE(myfield, '+', '', 'g'), ''), '0')) AS INTEGER) Then text/varchar values like "b3ad5" will also give numbers db=> select CAST(REGEXP_REPLACE(COALESCE('b3ad5','0'), '+', '', 'g') AS INTEGER) CAST(REGEXP_REPLACE(COALESCE(myfield,'0'), '+', '', 'g') AS INTEGER) Shows you how to use PostgreSQL CAST to convert from one data type into another e.g., a string into an integer, a string to date, a string to double etc. If you need to handle the possibility of the field having non-numeric text (such as "100bad") you can use regexp_replace to strip non-numeric characters before the cast. Some test cases to demonstrate: db=> select CAST((COALESCE(NULL,'0')) AS INTEGER) ĭb=> select CAST((COALESCE('','0')) AS INTEGER) ĭb=> select CAST((COALESCE('4','0')) AS INTEGER) ĭb=> select CAST((COALESCE('bad','0')) AS INTEGER) ĮRROR: invalid input syntax for integer: "bad" I had the same sort of need and found this to work well for me (postgres 8.4): CAST((COALESCE(myfield,'0')) AS INTEGER) ![]()
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