From: Greg Wilson <gvwilson@third-bit.com>
Date: Sat, 30 Nov 2013 17:07:50 +0000 (-0500)
Subject: SQL reference sheet
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=30425a2aba51c175f69beae20499424124b96747;p=swc-sql.git

SQL reference sheet
---

diff --git a/sql/novice/index.md b/sql/novice/index.md
index babcbe7..62c3ff6 100644
--- a/sql/novice/index.md
+++ b/sql/novice/index.md
@@ -36,6 +36,7 @@ Topics
 See Also
 --------
 *   [Instructor's Guide](guide.html)
+*   [Reference](reference.html)
 
 Resources
 ---------
diff --git a/sql/novice/reference.md b/sql/novice/reference.md
new file mode 100644
index 0000000..ea860f3
--- /dev/null
+++ b/sql/novice/reference.md
@@ -0,0 +1,122 @@
+---
+layout: lesson
+root: ../..
+title: SQL Reference
+level: novice
+---
+Basic Queries
+-------------
+
+Select one or more columns from a table:
+
+    SELECT column_name_1, column_name_2 FROM table_name;
+
+Select all columns from a table:
+
+    SELECT * FROM table_name;
+
+Get only unique results in a query:
+
+    SELECT DISTINCT column_name FROM table_name;
+
+Perform calculations in a query:
+
+    SELECT column_name_1, ROUND(column_name_2 / 1000.0) FROM table_name;
+
+Sort results in ascending order:
+
+    SELECT * FROM table_name ORDER BY column_name_1;
+
+Sort results in ascending and descending order:
+
+    SELECT * FROM table_name ORDER BY column_name_1 ASC, column_name_2 DESC;
+
+Filtering
+---------
+
+Select only data meeting a condition:
+
+    SELECT * FROM table_name WHERE column_name > 0;
+
+Select only data meeting a combination of conditions:
+
+    SELECT * FROM table_name WHERE (column_name_1 >= 1000) AND (column_name_2 = 'A' OR column_name_2 = 'B');
+
+Missing Data
+------------
+
+Use `NULL` to represent missing data.
+
+`NULL` is not 0, false, or any other specific value.
+Operations involving `NULL` produce `NULL`, so `1+NULL`, `2>NULL`, and `3=NULL` are all `NULL`.
+
+Test whether a value is null:
+
+    SELECT * FROM table_name WHERE column_name IS NULL;
+
+Test whether a value is not null:
+
+    SELECT * FROM table_name WHERE column_name IS NOT NULL;
+
+Grouping and Aggregation
+------------------------
+
+Combine values using aggregation functions:
+
+    SELECT SUM(column_name_1) FROM table_name;
+
+Combine data into groups and calculate combined values in groups:
+
+    SELECT column_name_1, SUM(column_name_2), COUNT(*) FROM table_name GROUP BY column_name_1;
+
+Joins
+-----
+
+Join data from two tables:
+
+    SELECT * FROM table_name_1 JOIN table_name_2 ON table_name_1.column_name = table_name_2.column_name;
+
+Writing Queries
+---------------
+
+SQL commands must be combined in the following order:
+`SELECT`, `FROM`, `JOIN`, `ON`, `WHERE`, `GROUP BY`, `ORDER BY`.
+
+Creating Tables
+---------------
+
+Create tables by specifying column names and types.
+Include primary and foreign key relationships and other constraints.
+
+    CREATE TABLE survey(
+        taken   INTEGER NOT NULL,
+        person  TEXT,
+        quant   REAL NOT NULL,
+        PRIMARY KEY(taken, quant),
+        FOREIGN KEY(person) REFERENCES person(ident)
+    );
+
+Programming
+-----------
+
+Execute queries in a general-purpose programming language by:
+
+*   loading the appropriate library
+*   creating a connection
+*   creating a cursor
+*   repeatedly:
+    *   execute a query
+    *   fetch some or all results
+*   disposing of the cursor
+*   closing the connection
+
+Python example:
+
+    import sqlite3
+    connection = sqlite3.connect("database_name")
+    cursor = connection.cursor()
+    cursor.execute("...query...")
+    for r in cursor.fetchall():
+        ...process result r...
+    cursor.close()
+    connection.close()