如何多次查询并最后关闭连接? [英] How to query multiple times and close the connection at the end?

问题描述

我想打开一个与mysql数据库的连接，并使用不同的查询检索数据.每次获取数据时都需要关闭连接吗?还是有更好的方法来多次查询并仅在最后关闭连接?

I'd like to open a connection to mysql database and retrieve data with different queries. Do I need to close the connection every time I fetch the data or is there a better way to query multiple times and close the connection only at the end?

当前，我这样做:

db = dbConnect(MySQL(), user='root', password='1234', dbname='my_db', host='localhost')

query1=dbSendQuery(db, "select * from table1")
data1 = fetch(query1, n=10000)
query2=dbSendQuery(db, "select * from table2")  ##ERROR !

我收到错误消息:

mysqlExecStatement(conn，statement，...)中的错误: RS-DBI驱动程序:(与挂起的行连接，在继续之前先关闭resultSet)

Error in mysqlExecStatement(conn, statement, ...) : RS-DBI driver: (connection with pending rows, close resultSet before continuing)

现在，如果我使用 dbClearResult(query1)清除结果，则需要重做连接(dbConnect ...)

Now if I clear the result with dbClearResult(query1) I need to redo the connection (dbConnect...)

是否有更好/有效的方法来首先获取所有内容，而不是每次都打开/关闭?

Is there a better/efficient way to fetch everything first instead of open/close every time?

推荐答案

尝试使用dbGetQuery(...)，而不要像这样使用dbSendQuery(...)和fetch()

Try dbGetQuery(...) instead of using dbSendQuery(...) and fetch() like this

db = dbConnect(MySQL(), user='root', password='1234', dbname='my_db', host='localhost')

query1=dbGetQuery(db, "select * from table1")
query2=dbGetQuery(db, "select * from table1")

从帮助页面:

"dbGetQuery"函数可以一次完成所有这些操作(提交语句，获取所有输出记录，并清除结果集).

The function ‘dbGetQuery’ does all these in one operation (submits the statement, fetches all output records, and clears the result set).

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