如何在 Shell 脚本中比较两个 Arrays

Question

I have two SQL files A.sql and B.sql. My requirement is to compare A.sql and B.sql and I need to check query which are present in A.sql is present in B.sql or not, if it is not there in B.sql then we need to print the contents which are there in A.sql and not there in B.sql. So basically i am storing the SQL Query upto Semicolon as one query and comparing both the arrays and printing the content.

Below is the Example

A.sql

Select * from emp;
Select * from dept;
Select * from student;
Select * from subject;

B.sql

Select * from emp;
Select * from dept;
Select * from student;

Output Excepted

Select * from subject;

Output what I am getting

Select * from emp;

Below is my script

 i=0
 while read -rd ';' first_sql
    do
      first_array[$i]=$first_sql
      i=$((i+1))
    done < A.sql 
  
 j=0
    while read -rd ';'second_sql
    do
      second_array[$j]=$second_sql
      j=$((j+1))
    done < B.sql 

for p in "${first_array[@]}"; do
  flag=false
  for q in "${second_array[@]}"; do
    if [[ $p == $q ]]; then
      echo "$p is in first_array"
      flag=true
      break
    fi
  done
  echo $flag 
echo "$p is not in first_array"
done

So now I am reading first SQL file ie A.sql upto Semicolon as a one query and storing it to the array.

 i=0
    while read -rd ';' first_sql
    do
      first_array[$i]=$first_sql
      i=$((i+1))
    done < A.sql 

So now I am reading Second SQL file ie B.sql upto Semicolon as a one query and storing it to the array.

j=0
while read -rd ';'second_sql
do
  second_array[$j]=$second_sql
  j=$((j+1))
done < B.sql 

Now I am comparing first_array and second_array and printing the contents which are present in first_array and not present in second_array outside the inner for loop.

for p in "${first_array[@]}"; do
  flag=false
  for q in "${second_array[@]}"; do
    if [[ $p == $q ]]; then
      echo "$p is in first_array"
      flag=true
      break
    fi
  done
  echo $flag 
echo "$p is not in first_array"
done

Can anyone please help with the above issue and let me know what is wrong.

Note: My one SQL query doesn't occupies single line, it will be more than 4-5 lines. Just for an example I have used a single line query.

Since my one SQL query is having more than 4-5 lines, so I am reading SQL query in while loop upto semicolon and storing it in a array and then i am comparing those two array to print the unmatched contents.

Thanks in advance!!!

Answer 1

You can do it with a one liner that uses comm to print out just the statements that appear in the first file, with a bit of pre and post processing to account for multi-line sql statements:

$  comm -z -23 <(perl -0777 -pe 's/;\n/;\x{0}/g' a.sql | sort -z) \
               <(perl -0777 -pe 's/;\n/;\x{0}/g' b.sql | sort -z) \
   | tr "\0" "\n"
Select * from subject;

(This does assume a GNU userland; other versions of comm and sort might not take the -z option).