MySQL - 如何获取列中的匹配总数

Question

我试过这段代码：

SELECT SUM(bookingstatus)
FROM beo_eventorder AS TotalBookingStatu
WHERE bookingstatus = 'Tentative';

但是这会返回0.表中有6个匹配项。 为什么这不会返回6？

列的屏幕截图：

Answer 1

您应该使用class RpcClient(object): def __init__(self): parameters = pika.URLParameters('amqp://djeo4uf8:f4323HekqiVXgt_vlnqPfJnvJruzszbn@sad-groundsel-39.bigwig.lshift.net:10722/fl1sX7CbcDds') parameters.socket_timeout = 5 self.connection = pika.BlockingConnection(parameters) self.channel = self.connection.channel() result = self.channel.queue_declare(exclusive=True) self.callback_queue = result.method.queue self.channel.basic_consume(self.on_response, no_ack=True, queue=self.callback_queue) def on_response(self, ch, method, props, body): if self.corr_id == props.correlation_id: self.response =loads( b64decode(body) ) def call(self, dict_data): self.response = None self.corr_id = str(uuid.uuid4()) self.channel.basic_publish(exchange='', routing_key='rpc_queue', properties=pika.BasicProperties( reply_to = self.callback_queue, correlation_id = self.corr_id, ), body=b64encode( dumps(dict_data) ) ) while self.response is None: self.connection.process_data_events() self.channel.close() self.connection.close() return self.response 代替rpc = RpcClient() response = rpc.call(payloadObj) ：

count

Answer 2

SUM添加了列上的所有元素，在您的情况下，它将所有字符串添加为0.您应该使用COUNT函数。