SQLite statement can be preceded by the keyword “EXPLAIN” or by the phrase “EXPLAIN QUERY PLAN” used for describing the details of a table.
Either modification causes the SQLite statement to behave as a query and to return information about how the SQLite statement would have operated if the EXPLAIN keyword or phrase had been omitted.
- The output from EXPLAIN and EXPLAIN QUERY PLAN is intended for interactive analysis and troubleshooting only.
- The details of the output format are subject to change from one release of SQLite to the next.
- Applications should not use EXPLAIN or EXPLAIN QUERY PLAN since their exact behavior is variable and only partially documented.
Syntax
syntax for EXPLAIN is as follows −
EXPLAIN [SQLite Query]
syntax for EXPLAIN QUERY PLAN is as follows −
EXPLAIN QUERY PLAN [SQLite Query]
Example
Consider COMPANY table with 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 us check the following sub-query with SELECT statement −
sqlite> EXPLAIN SELECT * FROM COMPANY WHERE Salary >= 20000;
This will produce the following result.
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 us check the following Explain Query Plan with SELECT statement −
SQLite> EXPLAIN QUERY PLAN SELECT * FROM COMPANY WHERE Salary >= 20000; order from detail ---------- ---------- ------------- 0 0 TABLE COMPANY