How to assign a variable value to a variable from another file?

Question

I have a sql file abc.sql having a SELECT SQL statement

SELECT COL FROM $D_SCHEMA.TABLE;

I have a shell script script.ksh

D_SCHEMA=DEV
EXEC_SQL=`cat abc.sql`
#echo $EXEC_SQL

#Function db_sql, which exports data to a csv file
db_sql "EXPORT TO /app/dev FILE ${EXEC_SQL}"

Now I am not able to assign the value to $D_SCHEMA from the sql file when the content is assigned to a variable in shell script.

Currently the variable is treated as a literal in the shell script.

echo $EXEC_SQL
SELECT COL FROM $D_SCHEMA.TABLE

Expected output

echo $EXEC_SQL
SELECT COL FROM DEV.TABLE

How do I go about solving this?

Answer 1

#!/bin/ksh

# one example using eval

D_SCHEMA=DEV
EXEC_SQL='SELECT COL FROM $D_SCHEMA.TABLE'

echo "$EXEC_SQL"
# output: SELECT COL FROM $D_SCHEMA.TABLE

eval new_var=\""$EXEC_SQL"\"
echo "$new_var"
# output: SELECT COL FROM DEV.TABLE