Reuse code that contains variables in same script bash - linux

Question

I have a small block of code in bash like below
#!/bin/bash
query="select * from table where id = ${row_id}"
row_id=1
echo "$query"
row_id=3
echo "$query"
row_id=4
echo "$query"
expected output is below
select * from table where id = 1
select * from table where id = 3
select * from table where id = 5
But I am getting nothing as output
I know I am referencing variable before assigning it.
The idea here is to use reusable code instead of writing the same code at many places
How can I achieve what I want

Answer 1

You can create a function and call the function at various place by assign variable to it
#!/bin/bash
# create a function with variable and write your command
# here your command is print the query
my_function_name(){
arg1=$1
echo "select * from table where id = ${arg1}"
}
# assign varaible
row_id=1
# print the ourput of function when above variable is assigned
query=$(my_function_name "$row_id")
echo $query
# assign varaible
row_id=2
# print the ourput of function when above variable is assigned
query=$(my_function_name "$row_id")
echo $query
# assign varaible
row_id=3
# print the ourput of function when above variable is assigned
query=$(my_function_name "$row_id")
echo $query

Answer 2

you should be getting
select * from table where id =
select * from table where id =
select * from table where id =
and as you already mentioned the reason is
I know I am referencing variable before assigning it.
One way to implement this
$ for row_id in 1 3 5;
do
echo "select * from table where id = $row_id";
done
select * from table where id = 1
select * from table where id = 3
select * from table where id = 5
UPDATE
Based on the comment
Here if row_id is a random variable I get as part of another query then
how do I get the correct query as my output
which is different from the posted question, better to define a function
$ getquery() { echo "select * from table where id = $1"; }
$ getquery $RANDOM
select * from table where id = 12907