Answers for "mysql alter column value"

update all rows mysql

UPDATE tableName SET columnName = yourValue;
#to update multiple columns:
UPDATE tableName SET column1 = value1, column2 = value2; #and so on

mysql change value

UPDATE [LOW_PRIORITY] [IGNORE] table_name 
SET 
    column_name1 = expr1,
    column_name2 = expr2,
    ...
[WHERE
    condition];

change column in mysql

#Alter is used
#alter table TableName change CurrentColumnName NewColumnName Specification(size);
alter table TableName change name firstname varchar(30);