Using java.sql.Date

I am using jdbc to call a sql q开发者_如何学运维uery ".... where mydate like '?%' " and I want to pass the parameter to the query with:

PreparedStatement ps;  
ps.setDate(1, new java.sql.Date.valueOf("2000-01-13"));

But this last line is not compiling, and I don't know why. When i enter the date directly into the query above, as in ".. where mydate like '2000-01-13%'", it works.

Apart from the basic compilation error (just remove new), I spot 2 serious problems:

1. Given the fact that LIKE works, your mydate field is apparently of a varchar type instead of a fullworthy date, datetime or timestamp type. This is recipe for problems. You should always use the right data type for the information the field holds.

2. % cannot be put after preparedstatement placeholder ?. It has to be set in the value directly. However, this works with String values only (and thus varchar field types). For a fullworthy date, datetime and timestamp type you'd rather use =, <, > or BETWEEN instead.

There are 2 solutions:

1. Change the data type of the field to be a real date, datetime or timestamp, so that you can use the proper SQL syntax such as WHERE mydate BETWEEN ? AND ?.

2. Use preparedStatement.setString(1, "2000-01-13%") instead and remove those singlequotes around the placeholder ? as well so that it ends like WHERE mydate LIKE ?.

See also:

• Preparedstatement tutorial
• MySQL data types

You'll want to use:

java.sql.Date.valueOf("2000-01-13")

That is, do not use new in front of it. By using new, you are telling the compiler you want to create a new object. Since valueOf is a static method, you do not need to create an object in order to call it.

Regardless, the reason it does not compile is because new java.sql.Date.valueOf("str") is not a valid statement. You would have to say new java.sql.Date() with parentheses if you wanted to create a new instance of Date, which you do, but by a different means.