SQLite的语句之前，可以由“EXPLAIN”的关键字或短语“EXPLAIN QUERY PLAN”，用于描述表的细节。
EXPLAIN - 语法
EXPLAIN 的语法如下-
EXPLAIN [SQLite Query]
EXPLAIN QUERY PLAN 的语法如下-
EXPLAIN QUERY PLAN [SQLite Query]
EXPLAIN - 示例
考虑 COMPANY 表，其中包含以下记录-
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 Learnfk 24 Houston 10000.0
现在，让无涯教程使用SELECT语句检查以下子查询-
sqlite> EXPLAIN SELECT * FROM COMPANY WHERE Salary >= 20000;
这将产生以下输出。
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
现在，让无涯教程使用SELECT语句检查以下解释查询计划:
SQLite> EXPLAIN QUERY PLAN SELECT * FROM COMPANY WHERE Salary >= 20000;order from detail ---------- ---------- ------------- 0 0 TABLE COMPANY
