SQL Basics Summary — Table Operations, WHERE, and Functions
A wrap-up of the SQL Basics series. Table definition, INSERT, SELECT, UPDATE, DELETE, filtering with WHERE, and transforming values with functions and CASE, organized with diagrams and tables.
The Big Picture of What SQL Basics Covered
This page organizes every command from the SQL Basics series into three views: table operations, filtering with WHERE, and transforming values with functions. Use the links to jump back to any article for review.
INSERT / UPDATE / DELETE move rows in and out of a table; SELECT reads them, WHERE filters them, and functions / CASE transform them.Set Up a Table and Move Data In and Out
The full data-handling flow: create a table → insert rows → read them → update / delete them. A SELECT result can then be tidied up with DISTINCT / ORDER BY / LIMIT.
| Category | Article | What you learn |
|---|---|---|
| Table definition | Creating and Modifying Tables | CREATE TABLE / PRIMARY KEY / NOT NULL / ALTER TABLE |
| Adding rows | INSERT | Named columns, omitted columns, multi-row inserts |
| Reading rows | SELECT | Choosing columns, AS aliases, WHERE basics |
| Updating / deleting rows | UPDATE and DELETE | Updating with SET; the danger of forgetting WHERE |
| Bulk delete | TRUNCATE | Difference from DELETE, the high water mark |
| Shaping results | DISTINCT, ORDER BY, LIMIT | Deduplication, sorting, row limits, OFFSET |
Filter Rows with WHERE, Transform Values with Functions
WHERE keeps only the rows that match a condition, while functions and CASE transform or classify the column values themselves. The two diagrams below organize the three WHERE deep-dive articles and the six function articles respectively.
WHERE keeps only the rows that match. The three families — logical operators, range & pattern, NULL & set — are covered in WHERE Deep Dive ①②③.SELECT and transform or classify them with arithmetic / string / math functions or IF / CASE. WHERE filters rows; functions change column values.| Category | Article | What you learn |
|---|---|---|
| WHERE ① | AND / OR / NOT | Logical operators and evaluation precedence |
| WHERE ② | BETWEEN and LIKE | Range filtering and pattern matching |
| WHERE ③ | IS NULL and IN | Three-valued logic, NULL checks, set matching |
| Functions ① | Arithmetic, concat, date | + - * / %, || / CONCAT, date functions |
| Functions ② | String functions | LENGTH / TRIM / REPLACE / UPPER / SUBSTR |
| Functions ③ | Math functions and COALESCE | ROUND / FLOOR / CEILING, NULL replacement |
| Functions ④ | IF / IIF | Switch a value on a single condition |
| Functions ⑤ | CASE for multi-condition branching | Simple CASE form and searched CASE form |
| Functions ⑥ | CASE in practice | ORDER BY / UPDATE / NULL handling |
Nice work!
You have now organized everything from table definition through adding, reading, updating, and deleting rows, filtering with WHERE, and transforming values with functions and CASE.
Combine these and you can already write many of the reporting queries you will see in real work. Go back to any article that interests you and try it on your own data.