How to assign a string column to variable and have it quoted in output in Bash script

In this post, I had asked a question as to how I can have my script read a CSV header and auto-quote string values; i.e. automatically wrap those columns whose data type is string and would need "" in order to be inserted into a SQL table. Apparently, this would be more than what Bash can handle?

At any rate, I'd welcome any help regarding how I can make the following script work: here, I have basically the same script but I tried to manually define separate columns and assign them to variables with col3 being a string column, hence quoted. Needless to say, it doesn't do what I want it to do (i.e. give me quoted values for all the string data under col3). Thanks!

#!/bin/bash

echo Path to to-be-imported CSV:
read csv_file
echo Table name to import into:
read table

echo "INSERT INTO $table VALUES" > SQL_INSERT_$table.txt
while read col1 col2 col3 col4
do
 echo "($col1 $col2 "$col3" $col4),"
done < <(tail -n +2 $csv_file) >> SQL_INSERT_$table.txt && sed -i '' '$ s/.$/;/' SQL_INSERT_$table.txt

Solution

Given the following csv file:

/tmp/csv:

Year,Make,Model,Description,Price
1997,Ford,E350,moon,-3000.00
1997,Ford,E350,moon,3000.00
1999,Chevy,Venture Extended Edition,,4900.00
1999,Chevy,Venture Extended Edition Very Large,,5000.00

And the code:

awk -F, 'OFS=FS {for (i=1;i<=NF;i++) {if (match($i, /^[0-9.-]+$/)==0) {printf "\"" $i "\""} else {printf $i}; if (i<NF) printf OFS}; printf "\n"}' /tmp/csv

It outputs:

All the string types of values are quoted.

"Year","Make","Model","Description","Price"
1997,"Ford","E350","moon",3000.00
1999,"Chevy","Venture Extended Edition","",4900.00
1999,"Chevy","Venture Extended Edition Very Large","",5000.00

The code is based on these assumptions:

There are no literal delimiters(the comma , here) inside the field values.
There are no literal newlines inside the field values.
There are no null values for the integer or the decimal fields.

If the assumptions don't stand for your data, you may need a CSV parser like this. And the exceptional field values should be well quoted, otherwise, even a parser won't know what to do.

BTW: Unless your data is very simple and the row number is a few, this is not the recommended way to manipulate the data. Many DBMS has an import/load utility that can be used in a program to do such a job.