SQL knowledge accumulation

 

1. insert a single quotation mark using insert into t_user values (''', 3 );

 

Ii. Message table Message: MessageID
SenderID: the sender ID (corresponding to the userID of the User table)
ReceiverID: receiver ID (corresponding to user table userID)
MessageTime sending time
Title Message Title
Body content

User table UserAccount:

UserID

UserAccount

UserName

To query messages related to a person (the sender or receiver is the same person ):
MessageId, sender name, receiver name, message title, sending time

Select m. messageid,

S. userid as sender ID,

S. username as sender name,

R. userid as receiver ID,

R. username as receiver name,

M. title
From t_message m join t_user s on m. senderid = s. userid
Join t_user r on m. receiveid = r. userid

 

3. query and use within a period of time

{And m. MessageTime >=# StartTime #}
{And m. MessageTime <DATEADD (DAY, 1, # EndTime #)}