If you are aspiring to become a SQL Developer, then you must learn these skills:
Database knowledge is a must.
Expertise in SQL is needed.
T-SQL and SSIS will help you get better at your job.
Soft skills are good communication skills, analytical skills, etc.
If you have all these, you can become a SQL Developer. Check out this SQL Server Course from Intellipaat, which has helped numerous professionals get better jobs. One such example is Prasanth, who enrolled in this course and achieved a career transition. I will also drop a video of a customer who has successfully achieved a career transition from mainframe developer to SQL Developer right after he enrolled in the course.
Intellipaat also provides complete learning through our Database Certification, go through and enroll now.