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I recently got a compute module 4 (CM4) donated to add support for NVMe in raspiBackup (See here for details). I'm used to use a Raspberry but never used a CM4 before so I had to ramp up on CM4 first. The following page describes how I managed to get a RaspbianOS (Buster) up and running on the CM4 and to boot from NVMe.
My CM4 specs: 1GB main memory, 32GB eMMC and 128GB NVMe from Hynix, no WiFi and a Waveshare Mini Base Board A (CM4-IO-BASE-A).
Note: The SD card slot on the Base Board cannot be used given my CM4 has eMMC and disables the SD card slot.
Parts
Hynix NVMe, CM4 and Waveshare Mini Base Board A (from top to bottom)
Parts assembled
Read more: Raspberry Compute Module 4 (CM4) setup guide on eMMC and NVMe
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I collected on the following pages various SQL queries and their results on a sample database. They use different SQL functions and will help to learn and understand SQL queries. In addition they help for look up most commonSQL syntax examples. A SQL beginner will get a good overview about the capabilities of SQL. Examples are given for select, count, union, where, having, order, limit, views, NULL, like, subselects and joins.
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SQL is not very easy to learn, in particular joins of multiiple tables are difficult to understand at a first glance. On the next pages it's explained for sql beginners how SQL joins work. Venn diagrams are used to explain how the tables are combined. In addition sample tables with sample data and sample joins are used to explain in detail the query input data results. SQL files to create the sample data and execute the queries can be downloaded. The samples are for mySQL and DB2.
If you want to see more complex sql joins in action visit Learning SQL by example for sql join examples and other SQL funktions as views, count, max, subselect and other.
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