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Scholar.DB.getNextID(table, column) -- get the lowest unused integer >0 in a DB column

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Dan Stillman 2006-08-26 08:02:17 +00:00
parent a457cdb493
commit 1410433e73
1 changed files with 30 additions and 0 deletions
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30
chrome/chromeFiles/content/scholar/xpcom/db.js
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@ -14,6 +14,7 @@ Scholar.DB = new function(){
this.statementQuery = statementQuery;
this.getColumns = getColumns;
this.getColumnHash = getColumnHash;
this.getNextID = getNextID;
this.beginTransaction = beginTransaction;
this.commitTransaction = commitTransaction;
this.rollbackTransaction = rollbackTransaction;
@ -342,6 +343,35 @@ Scholar.DB = new function(){
}
/**
* Find the lowest unused integer >0 in a table column
*
* Note: This retrieves all the rows of the column, so it's not really
* meant for particularly large tables.
**/
function getNextID(table, column){
var sql = 'SELECT ' + column + ' FROM ' + table + ' ORDER BY ' + column;
var vals = Scholar.DB.columnQuery(sql);
if (!vals){
return 1;
}
if (vals[0] === '0'){
vals.shift();
}
for (var i=0, len=vals.length; i<len; i++){
if (vals[i] != i+1){
break;
}
}
return i+1;
}
/////////////////////////////////////////////////////////////////
//