115 lines
4.1 KiB
C
115 lines
4.1 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <sqlite3.h>
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static const char* db_file = ":memory:"; // Create an in-memory database.
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void check_error(int result_code, sqlite3 *db);
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int select_callback(void* data, int column_count, char** columns, char** column_names);
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int main(void) {
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sqlite3 *db;
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int result_code;
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char *sql;
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char *insert_statements[4];
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sqlite3_stmt *compiled_statement;
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int i;
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// Open the database.
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result_code = sqlite3_open(db_file, &db);
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check_error(result_code, db);
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// Create the players table in the database.
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sql = "create table players("
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"id integer primary key asc, "
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"name text, "
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"score real, "
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"active integer, " // Store the bool value as integer (see https://sqlite.org/datatype3.html chapter 2.1).
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"jerseyNum integer);";
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result_code = sqlite3_exec(db, sql, NULL, NULL, NULL);
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check_error(result_code, db);
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// Insert some values into the players table.
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insert_statements[0] = "insert into players (name, score, active, jerseyNum) "
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"values ('Roethlisberger, Ben', 94.1, 1, 7);";
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insert_statements[1] = "insert into players (name, score, active, jerseyNum) "
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"values ('Smith, Alex', 85.3, 1, 11);";
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insert_statements[2] = "insert into players (name, score, active, jerseyNum) "
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"values ('Manning, Payton', 96.5, 0, 18);";
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insert_statements[3] = "insert into players (name, score, active, jerseyNum) "
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"values ('Doe, John', 15, 0, 99);";
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for (i=0; i<4; i++) {
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result_code = sqlite3_exec(db, insert_statements[i], NULL, NULL, NULL);
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check_error(result_code, db);
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}
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// Display the contents of the players table.
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printf("Before update:\n");
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sql = "select * from players;";
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result_code = sqlite3_exec(db, sql, select_callback, NULL, NULL);
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check_error(result_code, db);
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// Prepare the parametrized SQL statement to update player #99.
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sql = "update players set name=?, score=?, active=? where jerseyNum=?;";
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result_code = sqlite3_prepare_v2(db, sql, -1, &compiled_statement, NULL);
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check_error(result_code, db);
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// Bind the values to the parameters (see https://sqlite.org/c3ref/bind_blob.html).
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result_code = sqlite3_bind_text(compiled_statement, 1, "Smith, Steve", -1, NULL);
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check_error(result_code, db);
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result_code = sqlite3_bind_double(compiled_statement, 2, 42);
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check_error(result_code, db);
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result_code = sqlite3_bind_int(compiled_statement, 3, 1);
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check_error(result_code, db);
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result_code = sqlite3_bind_int(compiled_statement, 4, 99);
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check_error(result_code, db);
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// Evaluate the prepared SQL statement.
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result_code = sqlite3_step(compiled_statement);
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if (result_code != SQLITE_DONE) {
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printf("Error #%d: %s\n", result_code, sqlite3_errmsg(db));
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sqlite3_close(db);
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return result_code;
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}
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// Destroy the prepared statement object.
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result_code = sqlite3_finalize(compiled_statement);
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check_error(result_code, db);
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// Display the contents of the players table.
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printf("After update:\n");
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sql = "select * from players;";
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result_code = sqlite3_exec(db, sql, select_callback, NULL, NULL);
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check_error(result_code, db);
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// Close the database connection.
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sqlite3_close(db);
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return EXIT_SUCCESS;
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}
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/*
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Checks the result code from an SQLite operation.
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If it contains an error code then this function prints the error message,
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closes the database and exits.
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*/
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void check_error(int result_code, sqlite3 *db) {
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if (result_code != SQLITE_OK) {
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printf("Error #%d: %s\n", result_code, sqlite3_errmsg(db));
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sqlite3_close(db);
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exit(result_code);
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}
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}
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/* This callback function prints the results of the select statement. */
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int select_callback(void* data, int column_count, char** columns, char** column_names) {
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int i;
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for (i=0; i<column_count; i++) {
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printf(columns[i]);
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if (i < column_count-1) printf(" | ");
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}
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printf("\n");
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}
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