Question

I have the following script, which connects through ssh to a remote server and issues an SQL statement on it’s Postgresql database:

#!/bin/bash
db_query() {
    app_server="$1"
    sql_stmt="$2"
    psql_cmd="psql -d vdc --pset tuples_only -c '$sql_stmt'"
    rows_count=`ssh $app_server "sudo su - postgres -c \"$psql_cmd\""`

    echo "DB_QUERY: rows_count = $rows_count"
}

Now I’m trying to issue SELECT and INSERT statements to the following table:

CREATE TABLE pb_properties
(
  c_name character varying(255) NOT NULL,
  c_value character varying(255),
  CONSTRAINT pb_properties_pkey PRIMARY KEY (c_name)
)

This function works fine if I do a SELECT statement:

#!/bin/bash
source db_query.sh
db_query staging "SELECT * FROM pb_properties;"

>> Output: DB_QUERY: rows_count =  support-email | [e-mail]

But it does not work if I do an INSERT statement:

#!/bin/bash
source db_query.sh
db_query prestaging "INSERT INTO pb_properties (c_name, c_value) VALUES ('support-email', '[e-mail]');"

>> Output:
>>ERROR:  column "testname" does not exist
>>LINE 1: ...SERT INTO pb_properties (c_name, c_value) VALUES (testname, ...
                                                             ^
>>DB_QUERY: rows_count =

Now how can I do a successful INSERT statement with my db_query function? I already tried masking the values I tried to insert in many several ways, but none of them worked. I guess it has something to do with the combination of running the sql command through SSH and the different quotes i’m using `, ” and ‘.

Answer 1

Ok, since I cannot get the SQL statement with single quotes working at all with the db_query method in my question, I’m doing a workaround. On the remote Server, I’m redirecting the SQL statement into a temporary file. Then I can let psql read that file, then I don’t have to care about quotes anymore.

This is my new db_query function:

tmpfile=/tmp/pgquery

db_query() {
    app_server="$1"
    sql_stmt="$2"
    ssh $app_server "echo \"$sql_stmt\" > $tmpfile"
    psql_cmd="psql -d vdc --pset tuples_only -f $tmpfile"
    rows_count=`ssh $app_server "sudo su - postgres -c \"${psql_cmd}\""`

    echo "DB_QUERY: rows_count = $rows_count"
}

This now works with my initial statement:

db_query prestaging "INSERT INTO pb_properties (c_name, c_value) VALUES ('testname', 'testvalue');"

Anyway, if anybody has an hint how to get it working without a temporary file, I’d be glad to hear it.