Convert integer to string in PostgreSQL

Question

How do I convert an integer to string as part of a PostgreSQL query?

So, for example, I need:

SELECT * FROM table WHERE <some integer> = 'string of numbers'

where <some integer> can be anywhere from 1 to 15 digits long.

Diarrhea

What will you do if your string has leading zeros? – Footed

Answer 1

Because the number can be up to 15 digits, you'll need to cast to an 64 bit (8-byte) integer. Try this:

SELECT * FROM table
WHERE myint = mytext::int8

The :: cast operator is historical but convenient. Postgres also conforms to the SQL standard syntax

myint = cast ( mytext as int8)

---

If you have literal text you want to compare with an int, cast the int to text:

SELECT * FROM table
WHERE myint::varchar(255) = mytext

Gonzalo

Ah. I actually needed it the other way around (myint converted to varchar) but your answer was enough to guide me to the right place. I just did myint::varchar(255) = mytext and it works. Thanks! – Diarrhea

Strictly, this does not answer the question. The example was not the problem - converting an integer to a char/string was. But thanks, @Diarrhea – Aweless

@fred Not so: OP's actual problem was unsuccessfully trying to compare numeric and text values. This answer shows how to fix that by casting the text to a number (even though OP tried casting a number to text). – Gonzalo

@Gonzalo The question title and text says: "How do I convert an integer to string as part of a PostgreSQL query?". Then an example of when this could be relevant. In my case, I found this thread because I actually had to convert an integer to a string - not for comparison but for using inside an aggregate function that would fail, if the argument was not a string. In which case, this was not an answer to the question, as it literally reads atm. – Aweless

Answer 2

You can cast an integer to a string in this way

intval::text

and so in your case

SELECT * FROM table WHERE <some integer>::text = 'string of numbers'

Shawannashawl

This will not work if you're working with SpEL in jpa native queries. You'll have to use cast in that case. – Shepard

Answer 3

You could do this:

SELECT * FROM table WHERE cast(YOUR_INTEGER_VALUE as varchar) = 'string of numbers'

Robet

Answer 4

And if some integer which could be stored as string contains decimal points and you would want to compare decimal to decimal, below would help

select NULLIF('105.0', '')::decimal

SELECT * FROM table WHERE NULLIF('105.0', '')::decimal = 105.0

Below won't convert

select NULLIF('105.0', '')::int

select NULLIF('105.0', '')::integer

For this question you will just go by

select 105.3::text 

Mayramays

Answer 5

You can convert INT to VARCHAR as shown below. *The doc explains type conversion in detail:

postgres=# SELECT 123::VARCHAR;
 varchar
---------
 123
(1 row)

Or:

postgres=# SELECT CAST(123 AS VARCHAR);
 varchar
---------
 123
(1 row)

In addition, you can use pg_typeof() to check the type of 123 as shown below:

postgres=# SELECT pg_typeof(123);
 pg_typeof
-----------
 integer
(1 row)

And, if you set VARCHAR(2) to 123, the result is 12 as shown below:

postgres=# SELECT 123::VARCHAR(2);
 varchar
---------
 12
(1 row)

But, the type of 12 is VARCHAR(CHARACTER VARYING) rather than VARCHAR(2)(CHARACTER VARYING(2)) as shown below:

postgres=# SELECT pg_typeof(123::VARCHAR(2));
     pg_typeof
-------------------
 character varying
(1 row)

Cohla