What is the rationale for using static final strings for SQL statement strings?

Question

Many places seem to include using class constants for SQL strings as best practice.

So, instead of:

String sql = "select * from users";
PreparedStatement stmt = conn.prepareStatement(sql);

He prefers to do:

private static final String SQL_SELECT_USERS = "select * from users";

void someMethod() {
  ...
  PreparedStatement stmt = conn.prepareStatement(SQL_SELECT_USERS);
  ...
}

What are the benefits of the latter? It seems to me less readable.

Thanks.

Answer 1

A finalvariable cannot be changed, by mistake or otherwise. Declaring a statement line finalavoids this error:

String s = "select * from users";

// many lines of code
s = "temp";
// do something with s
// many lines of code
PreparedStatement stmt = conn.prepareStatement(sql);

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private final String SELECT_STAR_FROM = "select * from ";
private final String USERS_TABLE = "users";

// many lines of code
PreparedStatement stmt0 = conn.prepareStatement(SELECT_STAR_FROM + USERS_TABLE);

// this line would fail at run time
PreparedStatement stmt1 = conn.prepareStatement("selct * from users");

// this line fails at compile time and the compiler points you at it
PreparedStatement stmt0 = conn.prepareStatement(SELCT_STAR_FROM + USERS_TABLE);

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Answer 2

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PreparedStatement stmt = conn.prepareStatement("select * from users");

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