How to insert an Integer value in SQlite3 (ESP32 - Arduino IDE)? - c++

Question

Im trying to create a database which should contains an id (autoincrement) and an integer value by the sqlite3 library.
Now i have troubles to insert an integer value into the const char sql-query.
I tried to insert by %l, but it failed cause of const char type.
rc = db_exec(db1, "INSERT INTO test1 VALUES (?, %l)", random(0,200));
here is the full code:
void setup() {
Serial.begin(115200);
sqlite3 *db1;
int rc;
SPI.begin();
SD_MMC.begin();
sqlite3_initialize();
if (db_open("/sdcard/test1.db", &db1))
return;
//SD_MMC.remove("/test1.db");
if(SD_MMC.exists("/test1.db")){
Serial.println("Database exists");
}else{
rc = db_exec(db1, "CREATE TABLE IF NOT EXISTS test1 (id INTEGER PRIMARY KEY, content);");
if (rc != SQLITE_OK) {
sqlite3_close(db1);
return;
}
}
rc = db_exec(db1, "INSERT INTO test1 VALUES (?, ?)");
if (rc != SQLITE_OK) {
sqlite3_close(db1);
return;
}
rc = db_exec(db1, "SELECT * FROM test1");
if (rc != SQLITE_OK) {
sqlite3_close(db1);
return;
}
sqlite3_close(db1);
}
the excecute function of database:
int db_exec(sqlite3 *db, const char *sql) {
Serial.println(sql);
long start = millis();
int rc = sqlite3_exec(db, sql, callback, (void*)data, &zErrMsg);
if (rc != SQLITE_OK) {
Serial.printf("SQL error: %s\n", zErrMsg);
sqlite3_free(zErrMsg);
} else {
Serial.printf("Operation done successfully\n");
}
Serial.print(F("Time taken:"));
Serial.println(millis()-start);
return rc;
}

Answer 1

You need to convert your string to a const char array. The sample code is below, you can add values with this method.
int Value1 = Function1();
int Value2 = Function2();
String s_Command = "INSERT INTO test1 VALUES ('" + Value1 + "','" + Value2 + "');";
const char *c_Command = s_Command.c_str();
rc = db_exec(db1, c_Command);