mirror of
https://github.com/yasuhirokimura/db18
synced 2026-06-08 18:29:23 +00:00
Yasuhiro KIMURA
162 lines
3.4 KiB
C
162 lines
3.4 KiB
C
/*-
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* Copyright (c) 1997, 2019 Oracle and/or its affiliates. All rights reserved.
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*
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* See the file EXAMPLES-LICENSE for license information.
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*
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*/
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#include "ex_sql_utils.h"
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/*
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* This example shows how to create, maintain, and query an R-Tree index.
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*
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* A new R*Tree index is created as follows:
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* CREATE VIRTUAL TABLE <name> USING rtree(<column-names>);
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*
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* The usual INSERT, UPDATE, and DELETE commands work on an R*Tree index just
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* like on regular tables.
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*
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* Any valid query will work against an R*Tree index. Especially, you can
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* efficiently do inequality queries against the coordinate ranges with an
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* R-Tree index.
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*/
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const double data[8][4] = {{1, 4, 2, 4}, {3, 6, 4, 7},
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{5, 7, 1, 8}, {11, 14, 2, 4}, {10, 15, 1, 5},
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{8, 12,3, 6}, {9, 11, 7, 9}, {9, 14, 7, 10}};
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/* Create a 2-dimention rtree index. */
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int create_rtree(db)
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db_handle *db;
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{
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const char* sql;
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/*
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* create an rtree which has 5 cloumns: id, minx, maxX, minY, maxY.
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*/
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sql = "DROP TABLE IF EXISTS rtree_index;\n"
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"\tCREATE VIRTUAL TABLE rtree_index USING rtree(\n"
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"\tid,\n"
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"\tminX, maxX,\n"
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"\tminY, maxY\n"
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"\t);";
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return exec_sql(db, sql);
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}
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/* Insert rectangles into the rtree-index. */
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int populate_data(db)
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db_handle *db;
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{
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int i, j, rc, errflag;
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const char* sql;
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sqlite3_stmt* stmt;
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/* Prepare a statement for rtree insert. */
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sql = "INSERT INTO rtree_index VALUES(?, ?, ?, ?, ?)";
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sqlite3_prepare_v2(db, sql, (int)strlen(sql), &stmt, NULL);
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error_handler(db);
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errflag = 0;
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/* Insert 8 rectangles with the id from 1-8 into the rtree-index. */
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for (i = 0; i < 8; i++) {
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/* Bind id with the value i+1. */
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sqlite3_bind_int(stmt, 1, i + 1);
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error_handler(db);
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/*
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* Get the values of minX, maxX, minY, maxY from data[i] and
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* bind them.
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*/
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for (j = 0; j < 4; j++) {
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sqlite3_bind_double(stmt, j+2, data[i][j]);
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error_handler(db);
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}
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/* Execute the query expression. */
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sqlite3_step(stmt);
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/* Reset stmt when SQLITE_DONE. The sqlite3_reset() function
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* is called to reset a prepared statement object back to its
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* initial state, ready to be re-executed. Any SQL statement
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* variables that had values bound to them using the
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* sqlite3_bind_*() API retain their values.
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*/
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rc = sqlite3_errcode(db);
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switch(rc) {
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case SQLITE_DONE:
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sqlite3_reset(stmt);
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break;
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default:
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fprintf(stderr, "ERROR: %s. ERRCODE: %d\n",
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sqlite3_errmsg(db), rc);
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errflag = 1;
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break;
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}
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if (errflag)
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break;
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}
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/* Final cleanup. */
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sqlite3_finalize(stmt);
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error_handler(db);
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return errflag;
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}
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/* Query the rtree-index. */
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int query_rtree(db)
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db_handle *db;
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{
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const char* sql;
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/* Select all records in rtree_index. */
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sql = "SELECT * FROM rtree_index";
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exec_sql(db, sql);
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/*
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* Select the IDs of rectangles which are contained within the query
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* box (5, 15, 1, 8).
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*/
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sql = "SELECT id FROM rtree_index\n"
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"\tWHERE minX >= 5 AND maxX <= 15\n"
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"\tAND minY >= 1 AND maxY <= 8";
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exec_sql(db, sql);
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/*
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* Select the IDs of rectangles which overlap the query box
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* (5, 15, 1, 8).
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*/
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sql = "SELECT id FROM rtree_index\n"
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"\tWHERE maxX >= 5 AND minX <= 12\n"
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"\tAND maxY >= 3 AND minY <= 7";
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exec_sql(db, sql);
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return 0;
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}
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int
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main()
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{
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db_handle *db;
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/* Setup environment */
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db = setup("./ex_rtree.db");
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create_rtree(db);
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populate_data(db);
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query_rtree(db);
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/* End. */
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cleanup(db);
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return 0;
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}
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