Practical sql: a beginner’s Guide to Storytelling with Data pdfdrive com
SAVING TIME WITH VIEWS, FUNCTIONS, AND TRIGGERS
tải về 5.77 Mb. Chế độ xem pdf
|
| 15
SAVING TIME WITH VIEWS, FUNCTIONS, AND TRIGGERS Using Views to Simplify Queries Creating and Querying Views Inserting, Updating, and Deleting Data Using a View Programming Your Own Functions Creating the percent_change() Function Using the percent_change() Function Updating Data with a Function Using the Python Language in a Function Automating Database Actions with Triggers Logging Grade Updates to a Table Automatically Classifying Temperatures Wrapping Up Try It Yourself 16 USING POSTGRESQL FROM THE COMMAND LINE Setting Up the Command Line for psql Windows psql Setup macOS psql Setup Linux psql Setup Working with psql Launching psql and Connecting to a Database Getting Help Changing the User and Database Connection Running SQL Queries on psql Navigating and Formatting Results Meta-Commands for Database Information Importing, Exporting, and Using Files Additional Command Line Utilities to Expedite Tasks Adding a Database with createdb Loading Shapefiles with shp2pgsql Wrapping Up Try It Yourself 17 MAINTAINING YOUR DATABASE Recovering Unused Space with VACUUM Tracking Table Size Monitoring the autovacuum Process Running VACUUM Manually Reducing Table Size with VACUUM FULL Changing Server Settings Locating and Editing postgresql.conf Reloading Settings with pg_ctl Backing Up and Restoring Your Database Using pg_dump to Back Up a Database or Table Restoring a Database Backup with pg_restore Additional Backup and Restore Options Wrapping Up Try It Yourself 18 IDENTIFYING AND TELLING THE STORY BEHIND YOUR DATA Start with a Question Document Your Process Gather Your Data No Data? Build Your Own Database Assess the Data’s Origins Interview the Data with Queries Consult the Data’s Owner Identify Key Indicators and Trends over Time Ask Why |