CODEWITHSUNDEEP
iossqlite
Hasib Samad
Hasib Samad

Reputation: 1081

SQLite step() returning SQLITE_ROW even when table is empty

I am trying to fetch rows from a table in SQLite:

_tempPath = [[NSSearchPathForDirectoriesInDomains
                            (NSDocumentDirectory, NSUserDomainMask, YES)
                            objectAtIndex:0] stringByAppendingPathComponent:@"test.db"];

sqlite3         *pHandle;
sqlite3_stmt    *pStatementHandle;

NSLog(@"OPEN: %i ", sqlite3_open([_tempPath UTF8String], &pHandle));

const char *query = "select * from Transactions";

NSLog(@"PREP: %i", sqlite3_prepare (pHandle, query, -1, &pStatementHandle, NULL));

while(sqlite3_step(pStatementHandle) != SQLITE_DONE);
{
    NSLog(@"ROW");
}

sqlite3_finalize(pStatementHandle);

sqlite3_close(pHandle);

However, I am always getting exactly one empty row. Never matters whether the table is empty or full of entries.

The open() and prepare() commands are returning SQLITE_OK.

What is going wrong?

Upvotes: 2

Views: 3653

Answers (1)

Rob
Rob

Reputation: 437592

The problem is that you have a semicolon at the end of the while statement, so your code does nothing during the while loop, and will then just treat the NSLog("ROW"); as something it will do when the while loop is done. Thus, your code:

while (sqlite3_step(pStatementHandle) != SQLITE_DONE);
{
    NSLog(@"ROW");
}

is equivalent to doing:

while (sqlite3_step(pStatementHandle) != SQLITE_DONE)
{
    // do nothing
}

{
    NSLog(@"ROW");
}

As an aside, you really should be looking at the sqlite3_step return code, and if not SQLITE_ROW or SQLITE_DONE, display the error, if any. Thus your loop:

while (sqlite3_step(pStatementHandle) != SQLITE_DONE);
{
    NSLog(@"ROW");
}

should probably be:

int rc;
while ((rc = sqlite3_step(pStatementHandle)) == SQLITE_ROW) // note, no ";"
{
    NSLog(@"ROW");
}

if (rc != SQLITE_DONE)
    NSLog(@"%s: step error: %d: %s", __FUNCTION__, rc, sqlite3_errmsg(pHandle));

In your original rendition, if you had an error, would never exit the while loop.

Upvotes: 3

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