CODEWITHSUNDEEP
javajspjdbc
user5392553
user5392553

Reputation:

use resultset in a for loop

int i = 0;
while (i < size) {
    String s = username[i];

    String sql4 = "select books1,books2 from " + uname + "a," + s + "b where " + uname + "a.books1=" + s + "b.books2";
    ResultSet rs3 = con.createStatement().executeQuery(sql4);

    System.out.println(sql4);
    while (rs3.next()) {

        count = rs3.getRow();
    }
    i++;
    System.out.println(count);

After running this code the output should be 2,1,0,0 but instead output is 2,2,2,2.that is sql query for i=0

Upvotes: 0

Views: 261

Answers (2)

user5384964
user5384964

Reputation:

Use ResultSet.last() instead of while loop. See following example.

count = rs3.last() ? rs3.getRow() : 0;

BAD PRACTICES OF CODE

Additionally it seems bad statements of your code. You are executing a query, inside a loop which make worse your program in performance. You can use SQL queries using COUNT, JOIN and another techniques to get your output easily and efficiently with less code.

Upvotes: 1

singhakash
singhakash

Reputation: 7919

Initialize the count inside the loop

while (i < size) {

count=0;
//execute query
}

with your code its printing the previous value of count if no row found.

And instead of using while(rs3.next()) you can use select count(*) as cnt... and use 

if(rs3.next()){
count = rs3.getInt("cnt");
}

Upvotes: 0

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