May 16, 2021 SQLite
Before the SQLite statement, you can use the "EXPLAIN" keyword or the "EXPLAIN QUERY PLAN" phrase to describe the details of the table.
If the EXPLAIN keyword or phrase is omitted, any modifications will cause the query behavior of the SQLite statement and return information about how the SQLite statement operates.
Output from EXPLAIN and EXPLAIN QUERY PLAN is for interactive analysis and troubleshooting only.
Details of the output format may vary with the SQLite version.
Applications should not use EXPLAIN or EXPLAIN QUERY PLAN because their exact behavior is variable and only parts are logged.
EXPLAIN's syntax is as follows:
EXPLAIN [SQLite Query]
The syntax of EXPLAIN QUERY PLAN is as follows:
EXPLAIN QUERY PLAN [SQLite Query]
Suppose the COMPANY table has the following records:
ID NAME AGE ADDRESS SALARY ---------- ---------- ---------- ---------- ---------- 1 Paul 32 California 20000.0 2 Allen 25 Texas 15000.0 3 Teddy 23 Norway 20000.0 4 Mark 25 Rich-Mond 65000.0 5 David 27 Texas 85000.0 6 Kim 22 South-Hall 45000.0 7 James 24 Houston 10000.0
Now, let's check the Explain usage in the SELECT statement:
sqlite> EXPLAIN SELECT * FROM COMPANY WHERE Salary >= 20000;
This results in the following:
addr opcode p1 p2 p3 ---------- ---------- ---------- ---------- ---------- 0 Goto 0 19 1 Integer 0 0 2 OpenRead 0 8 3 SetNumColu 0 5 4 Rewind 0 17 5 Column 0 4 6 RealAffini 0 0 7 Integer 20000 0 8 Lt 357 16 collseq(BI 9 Rowid 0 0 10 Column 0 1 11 Column 0 2 12 Column 0 3 13 Column 0 4 14 RealAffini 0 0 15 Callback 5 0 16 Next 0 5 17 Close 0 0 18 Halt 0 0 19 Transactio 0 0 20 VerifyCook 0 38 21 Goto 0 1 22 Noop 0 0
Now, let's check the Explain Query Plan usage in the SELECT statement:
SQLite> EXPLAIN QUERY PLAN SELECT * FROM COMPANY WHERE Salary >= 20000;
order from detail ---------- ---------- ------------- 0 0 TABLE COMPANY