An Embeddable NoSQL Database Engine

UnQLite C/C++ API Reference - Delete Database Record.

Syntax

int unqlite_kv_delete(unqlite *pDb,const void *pKey,int nKeyLen);

Remove a record from the database.

Description

To remove a particular record from the database, you can use this high-level thread-safe routine to perform the deletion. You can also delete records using cursors via unqlite_kv_cursor_delete_entry().

Parameters

pDb	A pointer to a unQLite Database Handle.
pKey	Target record key.
nKeyLen	pKey length. If the nKeyLen argument is less than zero, then pKey is read up to the first zero terminator. If nKeyLen is non-negative, then it is the maximum number of bytes read from pKey.

Return value

UNQLITE_OK is returned on success. Any other return value indicates failure such as:

UNQLITE_NOTFOUND: Nonexistent record.

UNQLITE_BUSY: Another thread or process have a reserved or exclusive lock on the database. In which case, the caller should wait until the lock holder relinquish it.

UNQLITE_READ_ONLY: Read-only Key/Value storage engine.

UNQLITE_NOTIMPLEMENTED: The underlying KV storage engine does not implement the delete operation.

UNQLITE_PERM: Permission error.

UNQLITE_LIMIT: Journal file record limit reached (An unlikely scenario).

UNQLITE_IOERR: OS specific error. This error is considered harmful and you should perform an immediate rollback via unqlite_rollback().

UNQLITE_NOMEM: Out of memory (Unlikely scenario). This error is considered harmful and you should perform an immediate rollback via unqlite_rollback().

For a human-readable error message, you can extract the database error log via unqlite_config() with a configuration verb set to UNQLITE_CONFIG_ERR_LOG.

Example

int rc;
unqlite *pDb;

// Open our database;
rc = unqlite_open(&pDb,"test.db",UNQLITE_OPEN_READWRITE);
if( rc != UNQLITE_OK ){ return; }

//Store some records unqlite_kv_append, unqlite_kv_store...

//Delete a record

rc = unqlite_kv_delete(pDb,"SomeRecord",-1);

if( rc != UNQLITE_OK ){

const char *zBuf;

int iLen;

/* Extract database error log */

unqlite_config(pDb,UNQLITE_CONFIG_ERR_LOG,&zBuf,&iLen);

if( iLen > 0 ){

puts(zBuf);

}

if( rc != UNQLITE_BUSY && rc != UNQLITE_NOTFOUND ){

/* Rollback */
unqlite_rollback(pDb);

}

//Auto-commit the transaction and close our handle
unqlite_close(pDb);