What does the enumeration in the MySQL field refer to
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What does the enumeration in the MySQL field mean?
Mysql > createtablemeiju (f1enum ('1th, 2nd, 3rd, 4th, 5th, 6th))
QueryOK,0rowsaffected (0.92sec)
Mysql > descmeiju
+-- +
| | Field | Type | Null | Key | Default | Extra | |
+-- +
| | F1 | enum ('1, NULL, 3, 4, 5, 6) | YES | | NULL | |
+-- +
Mysql > insertintomeijuvalues (2)
Mysql > insertintomeijuvalues ("2")
Mysql > insertintomeijuvalues ("6")
The serial number is 12345
The content cannot be inserted without a serial number or a serial number.
Mysql > insertintomeijuvalues (8)
ERROR1265 (01000): Datatruncatedforcolumn'f1'atrow1
Mysql > insertintomeijuvalues ("8")
ERROR1265 (01000): Datatruncatedforcolumn'f1'atrow1
Mysql > select*frommeiju
+-+
| | F1 |
+-+
| | 1 |
| | 2 |
| | 2 |
| | 6 |
+-+
Change the meter
Mysql > altertablemeijumodifyf1enum ("a", "b", "c", "d", "e", "f")
QueryOK,4rowsaffected (0.39sec)
Records:4Duplicates:0Warnings:0
You can automatically match the record as a serial number to a new field value (amazing)
Mysql > select*frommeiju
+-+
| | F1 |
+-+
| | a |
| | b |
| | b |
| | f |
+-+
What does the enumeration in the MySQL field mean?
A record can have only one enumerated value, unlike set, which can be accumulated.
Mysql > insertintomeijuvalues (7)
ERROR1265 (01000): Datatruncatedforcolumn'f1'atrow1
Note that it is best to enter a worthwhile value in quotation marks or it will be treated as a sequence number.
When the quoted number does not meet the enumeration requirements, it will try to see if it is appropriate to use it as a sequence number.
Such as insertintomeijuvalues ("7")
7 insert the seventh value if it is not in the enumerated value. If there are no 7 values, an error will be reported.
The difference between collections and enumerations
1 collection can have 64 values enumerate 65535
The serial number of the collection is 124816 and the enumeration is 123456.
3 set A field value can have several values
+-+
| | F1 |
+-+
| | fpen m |
+-+
There can be only one enumeration.
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