Add SQL (without test support)

sql/README.md

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+# Introduction
+This code aims to be based on ISO-compliant, therefore database-agnostic.
+However, Data Definition Language (DDL) usually involves vendor variants.
+
+# Setup
+Create database structure: see ./structure/<VARIANT>/create.sql
+Load test data: see ./test/data/load.sql
+
+# Execution
+Execute SQL script: see /code/update_quality.sql
+TODO: Introduce test framework - vendor specific
+