i would like help with sql query which can find list of all table in a database which contain some data in it. just list of table with data excluding all the tables with no data on it .
In MySQL you can query the "information schema", however the numbers are only estimates, see https://dev.mysql.com/doc/refman/8.0/en/tables-table.html.
SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_ROWS > 0 OR DATA_LENGTH > 0
Related
Below is my example code:
db = QSqlDatabase.addDatabase('QSQLITE')
db.setDatabaseName('book.db')
db.open()
model = QSqlQueryModel()
model.setQuery("SELECT * FROM card")
self.tableView.setModel(model)
I am using QSqlQueryModel, Qtablevie, Sqlite3, and able to view all rows in my table. But i want to view only last two rows of my table which are newly inserted rows in to the table. The table has no "id" field and it has numaric and text fields. How is it possible?
Below is the table image:
If you want to get the last 2 elements ordered by any field that indicates the insertion order, in your case "rowid", then you have to use a filter in the SQL command like this:
model.setQuery("SELECT * FROM card ORDER BY rowid DESC LIMIT 2")
Another possible option is to filter the table using QSortFilterProxyModel but it is more inefficient.
I have a table as follows:
CREATE TABLE someTable (
user_id uuid,
id uuid,
someField string,
anotherField string,
PRIMARY KEY (user_id, id)
);
I know that there's a way to do paging in cassandra (https://docs.datastax.com/en/developer/java-driver/2.1/manual/paging/)
However, what I need to do is:
page trough entire table (it's large, so paging is required)
get all rows of a user_id
do something with these rows.
In short I need to fetch all the results of 1 user and do this for every record there is. (No, I don't have a unique list of user_ids here)
Also, I know I could do this programatically: paging through all the pages, assume i get it ordered by user_id, and append the last user_id (where rows are cut off) to the next page of results so data of that user gets in the same set.
However, I was hoping there would be a more elegant solution for this?
However, what I need to do is:
page trough entire table (it's large, so paging is required).
Assuming you don't know the **user_id**. And you want to fetch all the users data. To do this use token function to make a range query to get the user_ids.Displaying rows from an unordered partitioner with the TOKEN function something like select * from someTable where token(a_id) > token(other_id);
get all rows of a user_id
Now you know the user_id and want to fetch all the rows of that user_id. Use range query based on id starting from the MIN_UUID. Like:
select * from someTable where user_id = 123 and id > MIN_UUID limit 100
After that query choose the 100th uuid to fetch other rows. such that:
select * from someTable where user_id = 123 and id > [previous_quries_100th_id(uuid)] limit 100
Keep querying until you fetched all the rows.
do something with these rows.
It depends on you what you want to do with all of those rows. Use language specific ResultSet and iterate over rows to do something on there.
I'm trying to retrieve rows from a table where a subquery matches an variable. However, it seems as if the WHERE clause only lets me compare fields of the selected tables against a constant, variable or subquery.
I would expect to write something like this:
DATA(lv_expected_lines) = 5.
SELECT partner contract_account
INTO TABLE lt_bp_ca
FROM table1 AS tab1
WHERE lv_expected_lines = (
SELECT COUNT(*)
FROM table2
WHERE partner = tab1~partner
AND contract_account = tab1~contract_account ).
But obviously this select treats my local variable as a field name and it gives me the error "Unknown column name "lv_expected_lines" until runtime, you cannot specify a field list."
But in standard SQL this is perfectly possible:
SELECT PARTNER, CONTRACT_ACCOUNT
FROM TABLE1 AS TAB1
WHERE 5 = (
SELECT COUNT(*)
FROM TABLE2
WHERE PARTNER = TAB1.PARTNER
AND CONTRACT_ACCOUNT = TAB1.CONTRACT_ACCOUNT );
So how can I replicate this logic in RSQL / Open SQL?
If there's no way I'll probably just write native SQL and be done with it.
The program below might lead you to an Open SQL solution. It uses the SAP demo tables to determines the plane types that are used on a specific number of flights.
REPORT zgertest_sub_query.
DATA: lt_planetypes TYPE STANDARD TABLE OF s_planetpp.
PARAMETERS: p_numf TYPE i DEFAULT 62.
START-OF-SELECTION.
SELECT planetype
INTO TABLE lt_planetypes
FROM sflight
GROUP BY planetype
HAVING COUNT( * ) EQ p_numf.
LOOP AT lt_planetypes INTO DATA(planetype).
WRITE: / planetype.
ENDLOOP.
It only works if you don't need to read fields from TAB1. If you do you will have to gather these with other selects while looping at your results.
For those dudes who found this question in 2020 I report that this construction is supported since ABAP 7.50. No workarounds are needed:
SELECT kunnr, vkorg
FROM vbak AS v
WHERE 5 = ( SELECT COUNT(*)
FROM vbap
WHERE kunnr = v~kunnr
AND vkorg = v~vkorg )
INTO TABLE #DATA(customers).
This select all customers who made 5 sales orders within some sales organization.
In ABAP there is no way to do the query as in NATIVE SQL.
I would advice not to use NATIVE SQL, instead give a try to SELECT/ENDSELECT statement.
DATA: ls_table1 type table1,
lt_table1 type table of table1,
lv_count type i.
SELECT PARTNER, CONTRACT_ACCOUNT
INTO ls_table1
FROM TABLE1.
SELECT COUNT(*)
INTO lv_count
FROM TABLE2
WHERE PARTNER = TAB1.PARTNER
AND CONTRACT_ACCOUNT = TAB1.CONTRACT_ACCOUNT.
CHECK lv_count EQ 5.
APPEND ls_table1 TO lt_table1.
ENDSELECT
Here you append to ls_table1 only those rows where count is equals to 5 in selection of table2.
Hope it helps.
I have a very huge table in cassandra that consists of (caseid ,timestamp, activity)as columns with caseid and timestamp being the primary key.The values of caseid are getting repeated and I want to extract the 1st value of activity corresponding to a caseid and put it to another table(named initialActivity) that consists of only activity. Can someone please help me as to how I can acheive this using a cql query.Thanks.
Please try this
Insert into initialActivity() values
(select activity from preActivity where caseId = 111 LIMIT 1 );
Only first rows with column activity with caseId = 111 will get inserted into initialActivity table
Please refer this for more info
CQL
I have some 20 excel files containing data. all the tables have same columns like id name age location etc..... each file has distinct data but i don't know if data in one file is again repeated in another file. so i want to join all the files and the result st should contain distinct values. please help me out with this problem as soon as possible. i want the result set to be stored in an access database.
I would recomend either linking the sheets in acces, or importing the sheets as tabels.
Then from there try to determine using a DISTINCT select from the tables/sheets the keys required, and only selecting the records as required.
In SQL, you can use JOIN or NATURAL JOIN to join tables. I would look into NATURAL JOIN since you said all tables have the same values.
After that you can use DISTINCT to get distinct values.
I'm not sure if this is what you're looking for though: your question asks about excel but you've tagged it with SQL.
If you can use all the tables in one query, you can use a union to get the distinct rows:
select id, name, age, location from Table1
union
select id, name, age, location from Table2
union
select id, name, age, location from Table3
union
...
You can insert the records directly from the result:
insert into ResultTable
select id, name, age, location from Table1
union
....
If you only can select from one table at a time, you can skip the insert of rows that are already in the table:
insert into ResultTable
select t.id, t.name, t.age, t.location from Table1 as t
left join ResultTable as r on r.id = t.id
where r.id is null
(Assuming that id is a unique field identifying the record.)
It seems the unique set of data you want is this:
SELECT T1.name, T1.loc
FROM [Excel 8.0;HDR=YES;IMEX=1;DATABASE=C:\db1.xls;
].[Sheet1$] AS T1
UNION
SELECT T1.name, T1.loc
FROM [Excel 8.0;HDR=YES;IMEX=1;DATABASE=C:\db2.xls;
].[Sheet1$] AS T1
...but that you then want to arbitrarily apply a sequence of integers as id (rather than using the id values from the Excel tables).
Because Access Database Engine does not support common table expressions and Excel does not support VIEWs, you will have to repeat that UNION query as derived tables (hopefully the optimizer will recognize the repeat?) e.g. using a correlated subquery to get the row number:
SELECT (
SELECT COUNT(*) + 1
FROM (
SELECT T1.name, T1.loc
FROM [Excel 8.0;HDR=YES;IMEX=1;DATABASE=C:\db1.xls;
].[Sheet1$] AS T1
UNION
SELECT T1.name, T1.loc
FROM [Excel 8.0;HDR=YES;IMEX=1;DATABASE=C:\db2.xls;
].[Sheet1$] AS T1
) AS DT1
WHERE DT1.name < DT2.name
) AS id,
DT2.name, DT2.loc
FROM (
SELECT T2.name, T2.loc
FROM [Excel 8.0;HDR=YES;IMEX=1;DATABASE=C:\db1.xls;
].[Sheet1$] AS T2
UNION
SELECT T2.name, T2.loc
FROM [Excel 8.0;HDR=YES;IMEX=1;DATABASE=C:\db2.xls;
].[Sheet1$] AS T2
) AS DT2;
Note:
i want the result set to be stored in
an access database
Then maybe you should migrate the Excel data into a staging table in your Access database and do the data scrubbing from there. At least you could put that derived table into a VIEW :)
Join is to combine two tables by matching the values in corresponding columns. In result, you will get a merged table which consists of the first table, plus the matched rows copied from the second table. You can use DIGBD add-in for excel