Insert statement in Insert-php+mysql, why should there be a space before time

Insertphpmysqli

The data table is as follows:

#
Name
Type
Collation
Attributes
Null
Default
Extra
Action

1
Id
Int (10)

UNSIGNED
No
None
Auto_increment
Change
Drop
More

2
Author
CHAR (20)
Utf8_general_ci

No
None

Change
Drop
More

3
Addtime
Datetime

No
None

Change
Drop
More

4
Content
varchar (100)
Utf8_general_ci

No
None

Change
Drop
More

5
Reply
varchar (100)
Utf8_general_ci

No
None

Change
Drop
More
Check allwith selected:browse Change Drop Primary Unique Index

Print View Relation View propose table structure Move columns

ADD column (s) at End of table at Beginning of table Afteridauthor addtimecontentreply

• Indexesinformationspace Usagedata16kibindex0btotal16kibrow Statisticsformatcompactcollationutf8_general_cinext AUTOINDEX2CREATIONAPR at 10:51 AM

1. Write time only.
$sql = "INSERT into message ( addtime ,) VALUES (' 2015-04-22 08:33:46 ')";
Can be written with the following results:

Id
Primary key, auto-grow
Author
Author
Addtime
Message time
Content
Message content
Reply
Reply

Edit
Copy
Delete
1

2015-04-22 08:33:46

2. Follow the form to fill in the message.
$sql = "INSERT into message ( author , addtime , content ) VALUES (' $name ', ' $addtime ', ' $content ')";
Can write normally, let me puzzled is addtime addtime in front of why must have space?

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