HarmonyOS rdb删除一条数据，条件是msgId是空字符串，现在空字符串删除不掉

predicates.equalTo('msgId', msgId);
if (store !== undefined) {
  (store as relationalStore.RdbStore).delete(predicates, (err: BusinessError, rows: number) => {
    if (err) {
      console.error(`Failed to delete data. Code:${err.code}, message:${err.message}`);
      return;
    }
    console.info(`Delete rows: ${rows}`);
  })
}
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msgId为空字符串删除不掉该如何删除？