Develop Reference

Android sqlite - how to calculate the difference between 2 REAL entries in sqlite?

In Android/Java, I am trying to compute and store the difference between 2 values in sqlite when one value is entered.
My table looks like this:
When weights are added/stored in the table in the column 'Weight', the column 'Diff_Weight' shall receive "Weight(N) - Weight(N-1)". Example: the last cell of Diff_Weight (row 6) = 88.0 - 55.2 = 32.8. // Row 5 shall get '-0.7' etc. Their type is REAL (col Weight & col Diff_Weight).
This 32.8 should be calculated and added at the same time when 88.0 is added to the table.
So far, I have read lots of tutorials and can't figure how to proceed. (My code to create and insert in the DB is fine, but reading is somehow more complex).
My code to read the entry is very bad because I don't see how to set it up:
public Bouble getData() {
String selectQuery= "SELECT * FROM " + TABLE_NAME2 + " ORDER BY COL_4 DESC LIMIT 1";
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(TABLE_NAME2, null);
result2 = Double.valueOf(cursor.getString(cursor.getColumnIndex("Weight")));
result1 = Double.valueOf(cursor.getString(cursor.getColumnIndex("Weight")-1));
insertdata(result2-result1); //insert in row 6 of Diff_Weight
return
}
Can anybody help there?
If that is unclear, I was needing some help for the sqlite command AND the java to get the difference result.

Simplistically you can get the data by joining to the same table
SELECT a.id, a.weight, b.weight, (b.weight - a.weight) FROM TABLE_NAME2 a
join TABLE_NAME2 b on (b.id = a.id + 1);

One way is to use the lag() window function to get the value of the previous row (As ordered by id; using timestamps would be better but between splitting up the date and time into different columns and not using a date format that can be meaningfully sorted, this is easier.):
SELECT id, weight,
round(coalesce(weight - lag(weight, 1) OVER (ORDER BY id), weight), 1) AS diff_weight
FROM example
ORDER BY id
which gives
id weight diff_weight
---------- ---------- -----------
1 22.0 22.0
2 22.2 0.2
3 55.0 32.8
4 55.9 0.9
5 55.2 -0.7
6 88.0 32.8
You can make a view of this query use that like a normal table if you like. Generating the differences dynamically like this has the advantage that if an existing weight value changes, everything that depends on it doesn't have to be updated.

ok, after a long search, here is a possible result (sqlite + java):
first, you need to query the last row of the table...
...and handle the case if there is no row in your table (blank or new table)
then you must query the 'Weight' value from the known column 'Weight' (Y) and the row with ID you already have (X)
and when you have your value (last_weight), you need to write the difference (weight-last_weight) in the column 'Diff_Weight'.
Here is the code:
SQLiteDatabase db = this.getWritableDatabase();
//query the last row of the table
Cursor cursor = db.rawQuery("SELECT ID FROM TABLE_NAME2 ORDER BY ID DESC LIMIT 1", null);
cursor.moveToLast();
int lastID;
//handle the case if there is no row in your table
try {
lastID = cursor.getInt(0);
} catch (Exception e) {
lastID = 0;
}
Double lastWeight = 0.0;
//query the 'Weight' value
if (lastID >= 1) {
Cursor cursor2 = db.rawQuery("SELECT Weight FROM TABLE_NAME2 WHERE ID=" + lastID, null);
if (cursor2.moveToFirst()) { //this is boundary otherwise 'lastWeight' doesn't get the value
lastWeight= cursor2.getDouble(0);
}
} else {
lastWeight = 0.0;
}
//write the difference in the Diff_Weight column (=COL_5)
ContentValues cValues2 = new ContentValues();
//add your data in COL_1 to COL_4 here...
cValues2.put(COL_5, weight - lastWeight);
long id2 = db.insert(TABLE_NAME2, null, cValues2);
... And so you get the red figures in the column Diff_Weight from the table photo in the question.

How to get table names from join condition using gsqlarser?

I am trying to implement sqlparser and using gsqlparser from here. The source of the jar is in Java but I am implementing the same in Scala.
Below is my query which contains a join condition.
SELECT e.last_name AS name, e.commission_pct comm, e.salary * 12 "Annual Salary" FROM scott.employees AS e right join scott.companies as c on c.orgid = e.orgid and c.orgname = e.orgn WHERE e.salary > 1000 ORDER BY e.first_name, e.last_name
I was able to parse the query to read names & aliases of columns, where conditions, table names (checking the table names directly inside the query) as below.
val sqlParser = new TGSqlParser(EDbVendor.dbvsnowflake)
sqlParser.sqltext = "SELECT e.last_name AS name, e.commission_pct comm, e.salary * 12 \"Annual Salary\" FROM scott.employees AS e right join scott.companies as c on c.orgid = e.orgid and c.orgname = e.orgn WHERE e.salary > 1000 ORDER BY e.first_name, e.last_name"
val selectStmnt = sqlParser.sqltext
println("Columns List:")
for(i <- 0 until selectStmnt.getResultColumnList.size()) {
val resCol = selectStmnt.getResultColumnList.getResultColumn(i)
println("Column: " + resCol.getExpr.toString + " Alias: " + resCol
.getAliasClause().toString)
}
Output:
Columns List:
Column: e.last_name Alias: name
Column: e.commission_pct Alias: comm
Column: e.salary * 12 Alias: "Annual Salary"
I am trying to parse the join condition and get the details inside it
for(j <- 0 until selectStmnt.getJoins.size()) {
println(selectStmnt.getJoins.getJoin(j).getTable)
}
The problem here is there is only one join condition in the query, so the size returned is 1.
Hence the output is scott.employees.
If I do it a bit different as below using getJoinItems
println("Parsing Join items")
for(j <- 0 until selectStmnt.getJoins.size()) {
println(selectStmnt.getJoins.getJoin(j).getJoinItems)
}
I get the output by cutting off the first table from the join condition as below:
scott.companies as c on c.orgid = e.orgid and c.orgname = e.orgn
The method: getJoinItems() returns a list: TJoinItemList which I thought of traversing through. But even its size is 1.
println(selectStmnt.getJoins.getJoin(j).getJoinItems.size()) -> 1
I am out of ideas now. Could anyone let me know how can I parse the query's join condition and get the table names inside the join ?

I don't have access to Snowflake dialect in GSP but I mimicked this scenario with Teradata dialect using the following query and created a sql parser.
SELECT e.last_name as name
FROM department d
RIGHT JOIN
trimmed_employee e
ON d.dept_id = e.emp_id
WHERE e.salary > 1000
ORDER BY e.first_name
Here is the Groovy code of getting both the tables department, trimmed_employee. It boils down to iterating over each join and while doing so collect the current join's items (joinItems) using curJoin.joinItems only if it is not null.
stmt.joins.asList().collect { curJoin ->
[curJoin.table] + (curJoin?.joinItems?.asList()?.collect { joinItems -> joinItems.table } ?: [])
}.flatten()
Result:
department
trimmed_employee
For this simple sql that you mentioned in my case, the following code also works.
stmt.tables.asList()

How to auto adjust ID value (primary key) in oracle?

Right now I have created a sequence and a trigger to auto increment the ID value like this:
CREATE OR REPLACE TRIGGER "RTH"."TBL_USER_TRIGGER"
BEFORE INSERT ON TBL_USER
FOR EACH ROW
BEGIN
SELECT TBL_USER_SEQ.nextval
INTO :new.USR_ID
FROM dual;
END;
ALTER TRIGGER "RTH"."TBL_USER_TRIGGER" ENABLE;
Let say I have three rows:
User ID FIRSTNAME LASTNAME
====================================
1 John smith
2 James smith
3 Pat smith
When I delete the first row(1) I want the ID values to auto correct itself to correct numbers so that second row ID values becomes 1 and third row ID values becomes 2
Is it possible in oracle? or do I have do it through code as I am using Java to insert records into table when user submits a form.
Java DAO class:
public class RegistrationDAO {
public void insert(User user) {
try {
Connection con = DBConnection.getConnection();
String query = "insert into TBL_USER(USR_FIRST_NAME,USR_LST_NAME,USR_PRIMARY_EMAIL,USR_PASSWORD) values(?,?,?,?)";
PreparedStatement pst = con.prepareStatement(query);
pst.setString(1, user.getFirstName());
pst.setString(2, user.getLastName());
pst.setString(3, user.getEmail());
pst.setString(4, user.getPassword());
pst.executeUpdate();
} catch (Exception e) {
System.out.println("####Record insertion error in Registration DAO####");
System.out.println(e);
}
}
}

The simple answer is: "No, you don't want to do that." The purpose of an id is to uniquely identify each row. A sequential id also has the feature that it provides insertion order. It is not intended to change over time. Row 1 is Row 1 is Row 1.
If you want ordering, then declare the id to be the primary key and use a query such as this:
select t.*, row_number() over (order by usr_id) as seqnum
from t;

Ideally, you should not be changing USER ID values. But still if there is requirement. Then below are the steps.
Create a procedure to reset the sequence TBL_USER_SEQ. This is needed as you are resetting the USER ID values. So after resetting, whenever you insert new record, Sequence should start with proper value ( i.e. MAX USER_ID value of the table). So that there will be no gap in USER_ID
Write Delete Trigger on table which will adjust USER_ID values.
Procedure to reset sequence
CREATE OR REPLACE PROCEDURE reset_sequence_p (p_seq IN VARCHAR2, p_new_seq NUMBER)
AS
l_value NUMBER;
BEGIN
-- Select the next value of the sequence
EXECUTE IMMEDIATE 'SELECT ' || p_seq || '.NEXTVAL FROM DUAL' INTO l_value;
-- Alter the sequnce to increment by the difference
EXECUTE IMMEDIATE 'ALTER SEQUENCE ' || p_seq || ' INCREMENT BY ' || ( p_new_seq - l_value ) ;
-- Increment to next value after diference
EXECUTE IMMEDIATE 'SELECT ' || p_seq || '.NEXTVAL FROM DUAL' INTO l_value;
-- Set the increment back to 1
EXECUTE IMMEDIATE 'ALTER SEQUENCE ' || p_seq || ' INCREMENT BY ' || 1 ;
END reset_sequence_p;
Delete Trigger
CREATE OR REPLACE TRIGGER "RTH"."TBL_USER_TRIG_DEL"
BEFORE DELETE
ON TBL_USER
FOR EACH ROW
DECLARE
v_new_user_id_seq NUMBER;
PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
-- Update USER_ID value for all remaining records greater than USER_ID that got deleted.
UPDATE TBL_USER
SET USER_ID = USER_ID - 1
WHERE USER_ID > :old.USER_ID;
-- Retrieve max USER_ID available in table.
SELECT MAX (user_id) INTO v_new_user_id_seq FROM TBL_USER;
-- Call procedure to reset sequence
reset_sequence_p ('TBL_USER_SEQ', v_new_user_id_seq);
COMMIT;
END;
NOTE : Make sure that Primary key on table is disabled before execution of Delete statement.
I hope this helps.

JDBC execute big T-SQL query

I have big SQL script with creating temp tables and inserting data in them from selecting data from another tables, many inserts, like
SET #EndDate = DATEADD(dd, -1, #EndDate);
DECLARE #EndDatePlusOneDay SMALLDATETIME
SET #EndDatePlusOneDay = DATEADD(dd, 1, #EndDate);
CREATE TABLE #cntrs
(
ContractID DSIDENTIFIER,
ContractDateFrom dsdatetime,
ContractNumber dsvarfullname40,
ContractClientID DSIDENTIFIER,
ContractClientName VARCHAR(500),
CreditDateTo dsdatetime,
Amount dsmoney,
LoanDept dsmoney,
PledgeRate dsmoney,
CollatVal dsmoney,
WarrantyType dsfullname,
WarrantyNumber VARCHAR(20),
WarrantyDate dsoperday,
WarrantyQty dsmoney,
)
INSERT INTO #cntrs
SELECT c.ContractID,
cc.CreditDateFrom,
c.Number,
ti.InstitutionID,
(
CASE
WHEN ti.PropDealPart = 0 THEN ti.Name + ' ' + ti.Name1 + ' ' +
ti.Name2 + ' '
ELSE ti.Name
END
) AS ContractClientName,
cc.CreditDateTo,
c.Amount,
0 AS LoanDept,
70 AS PledgeRate,
0 AS CollatVal,
'' AS WarrantyType,
'' AS WarrantyNumber,
'19000101' AS WarrantyDate,
0 AS WarrantyQty
FROM dataTable1 c(NOLOCK)
INNER JOIN dataTable2 cc(NOLOCK)
ON c.ContractID = cc.ContractCreditID
INNER JOIN dataTable3 o(NOLOCK)
ON c.ContractID = o.ID
AND o.ObjectTypeID = 105
INNER JOIN dataTable4 p(NOLOCK)
ON o.CurrProtocolID = p.ProtocolID
INNER JOIN dataTable5 t(NOLOCK)
ON p.TransitionID = t.TransitionID
INNER JOIN dataTable6 n(NOLOCK)
ON t.TargetStateID = n.NodeID
INNER JOIN dataTable7 ti WITH(NOLOCK)
ON ti.InstitutionID = c.InstitutionID
WHERE 1 = 1
-- AND #BranchID IN (0, ISNULL(NULLIF(c.BranchExtId, 0), c.BranchID))
AND n.Brief IN ('Предоставл', 'НеОплВовр', 'Завершен')
AND cc.CreditDateFrom BETWEEN #StartDate AND #endDate
ORDER BY
cc.CreditDateFrom
IF OBJECT_ID('tempdb..#AccInner') IS NOT NULL
DROP TABLE #AccInner
CREATE TABLE #AccInner
(
ContractID NUMERIC(15, 0),
ResourceID NUMERIC(15, 0)
)
CREATE UNIQUE INDEX x1 ON #AccInner(ContractID)
DECLARE #DepParentID DSIDENTIFIER, -- Субконто КатегорияСредств
#DepRepaymentID DSIDENTIFIER, -- Субконто ТипОперВУ - Упл/Погаш
#DepAccrualID DSIDENTIFIER -- Субконто ТипОперВУ - Выд/Нач
SELECT #DepParentID = d.DepartmentID
FROM tDepartment d(NOLOCK INDEX = XAK3tDepartment)
WHERE d.Brief = 'КатСрдств'
UPDATE c
SET c.CollatVal = c.LoanDept * (c.PledgeRate / 100)
FROM #cntrs c
SELECT *
FROM #cntrs
ORDER BY
ContractDateFrom
I need execute this T-SQL code in one batch query. I plan to read T-SQL code from the file to String and execute this String at once.
How I can do this with JDBC for MS SQL Server?

You can always save this T-SQL code as MSSQL stored procedure and execute it using JDBC CallableStatement.

Hibernate and Mysql results don't match

I 'm using Hibernate connecting to mysql as database layer, the weird thing is for some reason
the result sets executed from Hibernate api java code are different from those executed directly from mysql. They are not a part of each other, they just look like no relationship.
Here's the Java code at Dao layer:
int totalPage = 0;
int reminder = total % pagination.getPageSize();
if(total == 0){
totalPage = 1;
pagination.setTotalPage(totalPage);
}else{
totalPage = reminder == 0 ? total / pagination.getPageSize() : (total - reminder) / pagination.getPageSize() + 1;
pagination.setTotalPage(totalPage);
}
pagination.setTotalRows(total);
pagination.setBeginAndEndPage(total);
final StringBuilder queryString = new StringBuilder();
queryString.append(" select a.target_id as itemId, a.isFree as isFree, ");
queryString.append(" ni.fullName as item, nc.fullName as category, a.downloadCount as downloadCounts from( ");
queryString.append(" select dldc.current_category_id, dldc.target_id, dldc.isFree, ");
queryString.append(" sum(dldc.counts) as downloadCount from download_log_day_count dldc ");
queryString.append(" group by dldc.current_category_id, dldc.target_id) as a ");
queryString.append(" left join item i on a.target_id = i.objectId ");
queryString.append(" left join name ni on i.nameId = ni.objectId ");
queryString.append(" left join category c on a.current_category_id = c.objectId ");
queryString.append(" left join name nc on c.nameId = nc.objectId ");
queryString.append(" order by downloadCounts desc");
List<ItemReportVO> reportList = (List<ItemReportVO>)getJpaTemplate().execute(new JpaCallback(){
#Override
public Object doInJpa(EntityManager em)
throws PersistenceException {
SQLQuery query = ((Session)em.getDelegate()).createSQLQuery(queryString.toString());
query.addScalar("itemId", Hibernate.LONG);
query.addScalar("isFree", Hibernate.BOOLEAN);
query.addScalar("item", Hibernate.STRING);
query.addScalar("category", Hibernate.STRING);
query.addScalar("downloadCounts", Hibernate.LONG);
query.setResultTransformer(Transformers.aliasToBean(ItemReportVO.class));
int firstResult = (pagination.getCurrentPage()-1) * pagination.getPageSize();
query.setFirstResult(firstResult);
if(token != null && "all".equals(token)){
int maxResult = pagination.getPageSize();
query.setMaxResults( maxResult );
}else{
int maxResult = pagination.getPageSize() > Integer.valueOf(token) ? Integer.valueOf(token) : pagination.getPageSize();
query.setMaxResults( maxResult );
}
return query.list();
}
});
When I set show_sql=true in Hibernate's config file, Hibernate prints the sql query below when Java code runs "return query.list();":
select a.target_id as itemId, a.isFree as isFree, ni.fullName as item, nc.fullName as category, a.downloadCount as downloadCounts
from(
select dldc.current_category_id, dldc.target_id, dldc.isFree, sum(dldc.counts) as downloadCount
from download_log_day_count dldc
group by dldc.current_category_id, dldc.target_id) as a
left join item i on a.target_id = i.objectId
left join name ni on i.nameId = ni.objectId
left join category c on a.current_category_id = c.objectId
left join name nc on c.nameId = nc.objectId
order by downloadCounts desc
limit ?
I always consider they should be the same, but it seems they are not, anybody can help me to adjust the java codes?

Hibernate will alter your query to apply limit that you coded via API setMaxResults(). It should also add rownum> for setFirstResult() but, in your case, it may be very first query.
You don't have to change anything as Hibernate applies those in database specific and correct way.
Is there any other difference that concerns you?