I have an application that works well. But I suspect that I can improve it if I optimize queries to the database. And I need suggestions.
This is part of my "select query":
private static final String SELECT = "SELECT " +
"dz.first_id AS first_id, " +
"dz._id AS _id, " +
"dz.att1 AS att1, " +
"dz.att2 AS att2, " +
"dz.att3 AS att3, " +
"dz.att4 AS att4, " +
"dz.att5 AS att5, " +
"d.var1 AS var1, " +
"d.name AS name, " +
"d.last_update AS last_update, " +
"d.image_url AS image_url, " +
"d.image_highlighted_url AS image_highlighted_url, " +
"d.var2 AS var2, " +
"d.type AS type, " +
"d.state AS state, " +
"d.sync AS sync, " +
"d.var3 AS var3 " +
"FROM table1 dz INNER JOIN table2 d " +
"ON d._id = dz.first_id ";
Cursor result = conn.rawQuery(SELECT, null);
*table1 and table2 have simple creation: only one _id integer PRIMARY KEY AUTOINCREMENT NOT NULL
It is useful to use views? Any other suggestion?
Thanks.
This query looks as cut and dry and they can get, I think your options are really either to see if you can somehow leave some unnecessary columns out of your select or alternatively to see that both dz.first_id and d._id have indexes setup. Perhaps add a index to dz with the following
CREATE INDEX index1 ON table1 (first_id);
Related
I am looking for a way of mapping an SQL result of type bool to a field of an entity.
Here's the code I need to work with:
#Formula("next_erds_id is null \n" +
"and exists(\n" +
" select * from processes p\n" +
" where p.message_uuid = message_uuid \n" +
" and exists(select * from process_tasks t\n" +
" where t.process_uuid = p.process_uuid and t.task_name = 'MP_MESSAGE_PROCESSED')\n" +
" and not exists(select * from process_tasks t\n" +
" where t.process_uuid = p.process_uuid and t.task_name = 'CH_NOTIFICATION_CREATED') \n" +
")")
private boolean canNotifyOnStartDeliveryAfter;
(Please ignore the field name. I've got no idea what it is supposed to mean...)
Of course, it does not work because it's not a valid MSSQL syntax.
Any idea how to fix it?
I'm trying to run a query, but I get an error when running it.
However, I'm using Intellij and when I use the copy string concatenation to clipboard feature, and run the query in the datagrip, the query runs fine (after putting in the parameters)
The error I am getting is "ERROR: syntax error at or near "tstoredarticle"\n Position: 199"
I find it a bit weird that it's showing there's a line change, after tstoredartiacle but besides that I don't see what's wrong.
What could be some issues that could cause a problem like that?
my query in intellij looks like this:
private ResultSet getHuaweiSqlQuery(Integer intBrandID, Integer intStorageID, Vector<Integer> vecArticleTypes, int iCurrencyID, int iContactSupplierID, int secondaryStorage, BigDecimal exchangeRate) throws SQLException {
return Hibernate3To4Utils.getConnection(session).createStatement().executeQuery("SELECT storedarticleid, "
+ " CASE WHEN storedarticle_storageid = " + intStorageID
+ " THEN id_storedarticleid_replacement ELSE"
+ " (SELECT COALESCE(id_storedarticleid_replacement, storedarticleid)"
+ " FROM etel.tstoredarticle x"
+ " WHERE tstoredarticle.storedarticle_articleid = x.storedarticle_articleid"
+ " AND x.storedarticle_storageid = " + intStorageID + ")"
+ " END as id_storedarticleid_replacement,"
+ " articlename,"
+ " articledescription, CASE WHEN price IS NULL THEN last_innprice*" + exchangeRate
+ " ELSE price END as last_innprice, id_modelids[1] as order_modelid, storedarticleamount-amount_in_order-amount_waiting as disponibelt,"
+ " amount_in_order, amount_in_bestilling, sum(tusedarticle.amount) as ant_artikler, articleid,amount_waiting, location"
+ " FROM etel.tstoredarticle"
+ " INNER JOIN etel.tarticle as b ON storedarticle_articleid = b.articleid"
+ " LEFT JOIN etel.tusedarticle ON usedarticle_storedarticleid = storedarticleid"
+ " AND ((tusedarticle.datesnap >= CAST(now() as date)-" + LOOK_BACK_DAYS
+ " AND usedarticlefromstorage = true) OR waiting = true)"
+ " LEFT JOIN etel.torder ON usedarticle_orderid = orderid AND torder.id_serviceplaceid = " + Constants.SERVICEPLACE
+ " LEFT JOIN etel.tsupplier_price ON id_articleid = b.articleid"
+ " AND tsupplier_price.id_serviceplaceid = " + Constants.SERVICEPLACE
+ " AND tsupplier_price.id_currencyid = " + iCurrencyID
+ " AND tsupplier_price.id_contactid_supplier = " + iContactSupplierID
+ " LEFT JOIN etel.tusedarticle as last_used on storedarticleid = last_used.usedarticle_storedarticleid"
+ " AND last_used.usedarticleid = (select MAX(latest_usedarticle.usedarticleid) from etel.tusedarticle as latest_usedarticle where"
+ " latest_usedarticle.usedarticle_storedarticleid = storedarticleid)"
+ " WHERE storedarticle_storageid IN(" + intStorageID + ", " + secondaryStorage + ") AND b.id_brandid = " + intBrandID
+ " AND id_articletypeid IN (" + getStringFromArray(vecArticleTypes.toArray()) + ")"
+ " AND tstoredarticle.passive <> true"
+ " GROUP BY storedarticleid,id_storedarticleid_replacement, articlename, articledescription, last_innprice, id_modelids[1],"
+ " storedarticleamount, amount_in_order, amount_in_bestilling, articleid,price,amount_waiting, location, last_used.datesnap"
+ " ORDER BY id_storedarticleid_replacement, storedarticleid");
}
and here's the same query after using the copy string concatenation to clipboard feature:
(this runs fine)
SELECT storedarticleid,
CASE WHEN storedarticle_storageid = ?
THEN id_storedarticleid_replacement ELSE
(SELECT COALESCE(id_storedarticleid_replacement, storedarticleid)
FROM etel.tstoredarticle x
WHERE tstoredarticle.storedarticle_articleid = x.storedarticle_articleid
AND x.storedarticle_storageid = ?)
END as id_storedarticleid_replacement,
articlename,
articledescription, CASE WHEN price IS NULL THEN last_innprice*?
ELSE price END as last_innprice, id_modelids[1] as order_modelid, storedarticleamount-amount_in_order-amount_waiting as disponibelt,
amount_in_order, amount_in_bestilling, sum(tusedarticle.amount) as ant_artikler, articleid,amount_waiting, location
FROM etel.tstoredarticle
INNER JOIN etel.tarticle as b ON storedarticle_articleid = b.articleid
LEFT JOIN etel.tusedarticle ON usedarticle_storedarticleid = storedarticleid
AND ((tusedarticle.datesnap >= CAST(now() as date)-42
AND usedarticlefromstorage = true) OR waiting = true)
LEFT JOIN etel.torder ON usedarticle_orderid = orderid AND torder.id_serviceplaceid = ?
LEFT JOIN etel.tsupplier_price ON id_articleid = b.articleid
AND tsupplier_price.id_serviceplaceid = ?
AND tsupplier_price.id_currencyid = ?
AND tsupplier_price.id_contactid_supplier = ?
LEFT JOIN etel.tusedarticle as last_used on storedarticleid = last_used.usedarticle_storedarticleid
AND last_used.usedarticleid = (select MAX(latest_usedarticle.usedarticleid) from etel.tusedarticle as latest_usedarticle where
latest_usedarticle.usedarticle_storedarticleid = storedarticleid)
WHERE storedarticle_storageid IN(?, ?) AND b.id_brandid = ?
AND id_articletypeid IN (?)
AND tstoredarticle.passive <> true
GROUP BY storedarticleid,id_storedarticleid_replacement, articlename, articledescription, last_innprice, id_modelids[1],
storedarticleamount, amount_in_order, amount_in_bestilling, articleid,price,amount_waiting, location, last_used.datesnap
ORDER BY id_storedarticleid_replacement, storedarticleid
Don't use string concatenation with dynamic text values to build a SQL statement.
For one, if the text values are supplied by a user, you're leaving yourself vulnerable to SQL injection attacks, allowing hackers to steal your data and delete your tables.
But you also have problems getting the text values quoted and escaped correctly.
Instead, use a PreparedStatement, where you place ? markers anywhere a dynamic value needs to go. That is the string in the clipboard.
Example: You're doing:
String name = "John";
String sql = "SELECT * FROM Person WHERE name = " + name;
That gives you this text at runtime:
SELECT * FROM Person WHERE name = John
which is wrong, because the text value needs to be quoted:
SELECT * FROM Person WHERE name = 'John'
You could try
String name = "John's Cross";
String sql = "SELECT * FROM Person WHERE name = '" + name + "'";
but that's also wrong, because this new text value has embedded quotes and would produce:
SELECT * FROM Person WHERE name = 'John's Cross'
To get it right, use a PreparedStatement:
String name = "John's Cross";
String sql = "SELECT * FROM Person WHERE name = ?";
PreparedStatement stmt = Hibernate3To4Utils.getConnection(session).prepareStatement(sql);
stmt.setParameter(1, name);
return stmt.executeQuery();
The JDBC driver will take care of any escaping needed, and thereby protects you from both SQL injection attacks and SQL syntax errors.
I need to execute an inner join on the same table. Below is the raw query I am currently executing.
String tagValueRowsSQL = "SELECT itv1.ItemTagValueID,itv1.FkItemID," +
"itv1.FkTagID,itv1.TagIndex,itv1.ValueIndex,itv1.Value,itv1.LastUpdateDateTime" +
" FROM tag.ItemTagValue itv1" +
" INNER JOIN tag.ItemTagValue itv2" +
" on itv1.fkTagID=" + tagIDsAndValues.get(LOCATION_STORE_CONFIG_TAG_NAME).getTagID() +
" and itv1.Value=" + storeId +
" and itv2.fkTagID = " + tagIDsAndValues.get(SENSOR_TYPE_TAG_NAME).getTagID() +
" and itv2.Value=" + sensorType;
RawSql rawSqlForSensorsInStoreAndOfType = RawSqlBuilder.parse(tagValueRowsSQL)
.columnMapping("itv1.ItemTagValueID", "ItemTagValueID")
.columnMapping("itv1.FkItemID", "FkItemID")
.columnMapping("itv1.FkTagID", "FkTagID")
.columnMapping("itv1.TagIndex", "TagIndex")
.columnMapping("itv1.ValueIndex", "ValueIndex")
.columnMapping("itv1.Value", "Value")
.columnMapping("itv1.LastUpdateDateTime", "LastUpdateDateTime")
.create();
Query<ItemTagValueModel> query = Ebean.find(ItemTagValueModel.class);
List<ItemTagValueModel> sensorsTagValueData = query.setRawSql(rawSqlForSensorsInStoreAndOfType).findList();
Executing the above using RawSQL seems pretty clumsy. How can I execute the above without using RawSQL? I checked this question Ebeans where columnA equals columnB in same table but I'm not sure how to apply that answer to my situation. Any help would be much appreciated.
I want to insert the SUM of Somme_versee (column in table Versement) in the column Versement_total.
This is a part of my code:
statement.executeUpdate("INSERT INTO Versement ( Nom , Prenom, Date , Somme_versee,Prix_du_logement, Nom_du_projet) VALUES('" + nom.getText() +"','" +prenom.getText() +"','" +date.getText() + "'," + verse.getText() + ", " + "(SELECT Prix_du_logement FROM Client WHERE Nom='"+ nom.getText() +"' AND Prenom='"+ prenom.getText() + "')," + " (SELECT Nom_du_projet FROM Client WHERE Nom='" + nom.getText()+ "' AND Prenom='" +prenom.getText() + "'))");
statement.executeUpdate("UPDATE Versement SET Versement_total= SUM(Somme_versee) " );
When executing I get this error: misuse of aggregate function SUM()
You should never do this in the same table. And it will get worse when the table gets more records. But what you seem to want is:
UPDATE Versement SET Versement_total = (SELECT SUM(Somme_versee) FROM Versement)
So the program is the connecting to a .mdb file as our data base. I have written all the other code to the program and know it works fine but I am now having trouble with a complex SQL statement being passed as a parameter to a createQuery(Sring, int) method.
There are two tables
Person, which has Name, Id, City, State
Classes, which has Id, Course, Grade
The intended purpose of this line is to print out "Name and Id" from a table of Persons and also print "Course and Grade" from the Classes table. The query only prints entries with matching Id's(Person.Id = Classes.Id), in a specific Course('CSC 225'), and that have a Grade > 70.
We never were taught the SQL statements in any depth so my basic understanding has concocted the following lines of code.
String s = "SELECT " + personTableTitle + ".Name, " + personTableTitle + ".Id, " +
classesTableTitle + ".Course, " + classesTableTitle + ".Grade FROM " +
personTableTitle + " " + classesTableTitle + " WHERE " +
personTableTitle + ".ID = " + classesTableTitle + ".Id AND " +
"Course = 'CIS 225' AND " + classesTableTitle + ".Grade > 70 AND " +
personTableTitle + ".Id = ? AND " + classesTableTitle + ".Id = ?";
System.out.print(s); // Double check of my SQL Statement before passing
db.createQuery(s, 4);
I have been playing with this SQL statement since Wednesday night and haven't been having much luck.
I only see two problems. Sql needs commas between the table names in the FROM clause, i.e. ...FROM table1, table2 WHERE.... So change your line to
personTableTitle + ", " + classesTableTitle + " WHERE " +
This next one might not be a problem, but it's a good idea to include the table name in front of every field reference.
classesTableTitle + ".Course = 'CIS 225' AND " + classesTableTitle + ".Grade > 70 AND " +
You should definitely try your query directly on the database (console or GUI). Once your query is valid, you'll be able to translate it very quickly back into Java.
Otherwise, it's good practice to add an alias to tables; for example:
select *
from Person P, Classes C
where P.Name = 'joe' and P.id = C.id
You may also need to do an outer join to get your data (look at how to do joins for your database).
Here's what I would suggest for SQL code
String s = "SELECT P.Name, P.Id, ";
s = s + "C.Course, C.Grade ";
s = s + "FROM Person P ";
s = s + "JOIN Classes C ";
s = s + "ON P.ID = C.ID ";
s = s + "WHERE Course = 'CIS 225' AND C.Grade > 70;";
I split up each assignment into its own line.
Solved it everyone, thanks for the help.
I started rewriting it using the suggestions posted and came up with this as the string:
String s = "SELECT Person2.Name, Person2.Id, Classes.Course, Classes.Grade FROM Person2, Classes WHERE Classes.Id = Person2.Id AND Classes.Course = 'CIS 225' AND Classes.Grade >70";
It works so I can make it more presentable now. The reason I am using my variable names from java in the original post was that is what the teacher wanted. She is very stubborn and has taken off points from my material for things as simple as writings += whatever; instead of s = s + whatever;