5.3. Example - Get List of Databases

5.3. Example - Get List of Databases
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The examples in this section show a procedure to return a list of the databases known to the server (which are stored in the pg_database table).

Note that the connect command does not specify a username or password. This would usually fail, unless the credentials are provided through some other means such as the environment variables.

The first example uses the pg_exec function.

Example 5.3. Connect and get list of databases - pg_exec

proc getDBs { {host "localhost"} {port "5432"} } {
    set conn [pg_connect -conninfo "host=$host port=$port dbname=template1"]
    set res [pg_exec $conn "SELECT datname FROM pg_database ORDER BY datname"]
    set datnames {}
    set ntups [pg_result $res -numTuples]
    for {set i 0} {$i < $ntups} {incr i} {
        lappend datnames [lindex [pg_result $res -getTuple $i] 0]
    }
    pg_result $res -clear
    pg_disconnect $conn
    return $datnames
}

Here is the same procedure, using pg_select to iterate over the returned rows.

Example 5.4. Connect and get list of databases - pg_select

proc getDBs { {host "localhost"} {port "5432"} } {
    set conn [pg_connect -conninfo "host=$host port=$port dbname=template1"]
    set datnames {}
    pg_select $conn "SELECT datname FROM pg_database ORDER BY datname" data {
        lappend datnames $data(datname)
    }
    pg_disconnect $conn
    return $datnames
}

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