postgres varchar needs casting

Question

I have 2 tables in 2 different schemas scha schb (e.g) and in scha I have a several tables that are all made of varchar as I had to format some data [it was part of the task]

now I have the same tables but with different types in schb.

The problem is this, Wherever I have a type which involves numbers (money, numerical, date), it's giving me an error to CAST.

Is there a way where I can CAST, without the need of copying one coloumn after another (copying it all in one go)

for example

INSERT INTO schb.customer
SELECT "col1", "col2" "col3 **(needs casting)**...."
FROM scha.customer

Thanks

Answer 1

A SELECT clause is not a list of columns, it is a list of expressions (which usually involve columns). A type cast is an expression so you can put them right into your SELECT. PostgreSQL supports two casting syntaxes:

CAST ( expression AS type )
expression::type

The first is standard SQL, the :: form is PostgreSQL-specific. If your schb.customer.col3 is (for example) numeric(5,2), then you'd say:

INSERT INTO schb.customer (col1, col2, col3)
SELECT col1, col2, cast(col3 as numeric(5,2))
FROM scha.customer

-- or

INSERT INTO schb.customer (col1, col2, col3)
SELECT col1, col2, col3::numeric(5,2)
FROM scha.customer

Note that I've included the column list in the INSERT as well. You don't have to do that but it is a good idea as you don't have to worry about the column order and it makes it easy to skip columns (or let columns assume their default values with explicitly telling them to).