SQL is the universal language for relational data — battery production teams use it to query MES databases, pull cell-formation history, audit pack genealogy, and feed analytics platforms with structured data. As a hard skill it requires fluency in joins (inner, outer, anti), window functions, aggregation patterns, query plan reading, and the index-design discipline that determines whether a yield query returns in 200ms or 20 minutes. Engineers and analysts apply this when reconstructing a cell's life from manufacture to field failure, when pulling a daily yield extract for the morning standup, and when designing the schema that ties pack IDs to cell IDs to test records.
