Update chapter13.md

chapter13.md

@@ -1 +1,19 @@
+## Chapter 13: Database Integration
+With LangChain, you can integrate with databases and build systems that answer questions based on structured data.
 
+```
+from langchain import OpenAI, SQLDatabase, SQLDatabaseChain
+
+# 
+db = SQLDatabase.from_uri("sqlite:///chinook.db")
+
+# LLM
+llm = OpenAI(temperature=0)
+
+# 
+db_chain = SQLDatabaseChain(llm=llm, database=db, verbose=True)
+
+# 
+query = "How many tracks are there in the album with ID 1?"
+print(db_chain.run(query))
+```