How to enable Foreign Key constraint in SQLITE with Objective C

Question

Today I noticed that Foreign key constraint on my SQLite table does not work. After reading on Stack Overflow, I found out that this should be enabled. So, I was looking for code snippet for doing that. So far, I could only find this:

[self.db executeUpdate:@"PRAGMA foreign_keys=ON"];

But this does not seem to work for me, as compiler always complains. I saw people use this line for FMDatabase type (I don't even know what is it). So, how do I enable foreign key constraint, if I open database connection like this:

- (void) openDatabase
{
    const char* databaseFile = [[self pathToDatabaseFile:@"readlater.sql"] UTF8String];
    sqlite3 *connection;
    if (sqlite3_open(databaseFile, &connection) != SQLITE_OK) {
        return;
    }
    self.db = connection;
}

Or should it be done while creating tables? Thank you.

The FMDatabase class is part of the FMDB library, a thin Objective-C wrapper around the SQLite C API. Using FMDB can greatly simplify your SQLite code. — Rob
– Rob, Commented Jun 20, 2014 at 16:31
@Rob, thank you for clearing this out for me. I will read look into it. — sermilion
– sermilion, Commented Jun 20, 2014 at 16:34

CL. · Accepted Answer · 2014-06-20 14:23:29Z

4

When you are using the SQLite C API directly, you must also use a C function to execute SQL commands:

sqlite3_exec(connection, "PRAGMA foreign_keys = on", NULL, NULL, NULL);

answered Jun 20, 2014 at 14:23

CL.

182k18 gold badges241 silver badges282 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

sermilion Over a year ago

Hi, thank you for your reply. Should I insert this line before each SELECT/INSERT/... statement?

ixx Over a year ago

What has to be done? I executed PRAGMA foreign_keys = ON; at application start, as the only statement in a transaction, and in the next transaction I execute PRAGMA foreign_keys; and it still returns 0.

CL. Over a year ago

@Ixx To ask a question, use the "Ask Question" button.

CL. Over a year ago

This answer ("call sqlite3_exec()") would not be the same as for your question.

Collectives™ on Stack Overflow

How to enable Foreign Key constraint in SQLITE with Objective C

1 Answer 1

4 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related