Print column names only once in shell script - mysql

Question

Here is my shell script and It is working fine without any errors. But i want to get output differently.
Script:
#!/bin/bash
DB_USER='root'
DB_PASSWD='123456'
DB_NAME='job'
Table_Name='status_table'
#sql=select job_name, date,status from $DB_NAME.$Table_Name where job_name='$f1' and date=CURDATE()
file="/root/jobs.txt"
while read -r f1
do
mysql -N -u$DB_USER -p$DB_PASSWD <<EOF
select job_name, date,status from $DB_NAME.$Table_Name where job_name='$f1' and date=CURDATE()
EOF
done <"$file"
Source Table:
mysql> select * from job.status_table
+---------+----------+------------+-----------+
| Job_id | Job Name | date | status |
+---------+----------+--------+---------------+
| 111 | AA | 2016-12-01 | completed |
| 112 | BB | 2016-12-01 | completed |
| 113 | CC | 2016-12-02 | completed |
| 112 | BB | 2016-12-01 | completed |
| 114 | DD | 2016-12-02 | completed |
| 201 | X | 2016-12-03 | completed |
| 202 | y | 2016-12-04 | completed |
| 203 | z | 2016-12-03 | completed |
| 111 | A | 2016-12-04 | completed |
+---------+----------+------------+-----------+
Input text file
[rteja#server0 ~]# more jobs.txt
AA
BB
CC
DD
X
Y
Z
A
ABC
XYZ
Output - Supressed coumn names
(mysql -N -u$DB_USER -p$DB_PASSWD <<EOF)
[rteja#server0 ~]# ./script.sh
AA 2016-12-01 completed
BB 2016-12-01 completed
Output - without Suppressed column names, output printing the columns names for every loop iteration.
(mysql -u$DB_USER -p$DB_PASSWD <<EOF)
[rteja#server0 ~]# ./script.sh
job_name date status
AA 2016-12-01 completed
job_name date status
BB 2016-12-01 completed
Challenges:
1. Want to print column names only once in output and the result i want to store in CSV file.
2. I don't want to expose password & username in code to everyone. Is there way to hide like i heard we can create environmental variables and call it in the script. And we can set the permissions for the environmental variable file to prevent everyone to access it, and only our should be able to access it.

Answer 1

Rather than executing a select query multiple times you can run a single query as:
job_name in ('AA','BB','CC'...)
To do that first read complete file in an array using mapfile:
mapfile -t arr < jobs.txt
Then format the array values into a list of values suited for IN operator:
printf -v cols "'%s'," "${arr[#]}"
cols="(${cols%,})"
Display your values:
echo "$cols"
('AA','BB','CC','DD','X','Y','Z','A','ABC','XYZ')
Finally run your SQL query as:
mysql -N -u$DB_USER -p$DB_PASSWD <<EOF
select job_name, date,status from $DB_NAME.$Table_Name
where job_name IN "$cols" and date=CURDATE();
EOF
To securely connecting to MySQL use login-paths (.mylogin.cnf)
As per MySQL manual:
The best way to specify server connection information is with your .mylogin.cnf file. Not only is this file encrypted, but any logging of the utility execution does not expose the connection information.