Mysql modifies the field type and modifies the field name.

Mysql modify field type:

-You can modify the field type, type length, default value and comments?

-Modify fields?

Alter? Table? Table name? Modify? Column? Field name? New data type? New length? New default value? New notes; ? - ? Columns can be omitted?

Alter? Table? Table 1? Modify? Column? column 1？ Decimal (10, 1)? Default? NULL？ Comments? Note'; ? - ? Normal. Can I modify the field type, type length, default value and comments?

Mysql modifies the field name:?

Alter? Table? Table name? Change? Old field name? New field name? New data type;

Alter? Table? Table 1? Change? column 1？ column 1？ varchar( 100)？ Default? 1.2? Comments? Note'; ? - ? Normal. At this time, the field name has not been changed. Can I modify the field type, type length, default value and comments?

Alter? Table? Table 1? Change? column 1？ Column 2? Decimal (10, 1)? Default? NULL？ Comments? Notes? - ? Normal. Can I modify the field name, field type, type length, default value and comments?

Alter? Table? Table 1? Change? Column 2? column 1？ Decimal (10, 1)? Default? NULL？ Comments? Notes? - ? Normal. Can I modify the field name, field type, type length, default value and comments?

Alter? Table? Table 1? Change? column 1？ Column 2; ? - ? Report an error