Create Temporary Table with Select and Values - sql

I'm trying to create a temporary table in Hive as follows:
CREATE TEMPORARY TABLE mydb.tmp2
AS SELECT * FROM (VALUES (0, 'abc'))
AS T (id , mystr);
But that gives me the following error:
SemanticException [Error 10296]: Values clause with table constructor not yet supported
Is there another way to create a temporary table by explicitly and directly providing the values in the same command?
My ultimate goal is to run a MERGE command, and the temporary table would be inserted after the USING command. So something like this:
MERGE INTO mydb.mytbl
USING <temporary table>
...

Use subquery instead of temporary table:
MERGE INTO mydb.mytbl t
USING (SELECT 0 as id, 'abc' as mystr) tmp on tmp.id = t.id

Hive does not support values constructor yet. You can achieve this using below query:
CREATE TEMPORARY TABLE mydb.tmp2
AS SELECT 0 as id, 'abc' as mystr;
For merge, you can use temporary table as below:
merge into target_table
using ( select * from mydb.tmp2) temp
on temp.id = target_table.id
when matched then update set ...
when not matched then insert values (...);

Related

Save return values from INSERT...RETURNING into temp table (PostgreSQL)

I have a table table1 with columns id,value1 and value2.
Also I have a query
INSERT INTO table1(value1,value2) SELECT value3,value4 FROM table2 RETURNING id
that returns set of ids.
I want to store return values (these ids) in some temp table. Something like that:
INSERT INTO TEMP temp1 INSERT INTO table1(value1,value2) SELECT value3,value4 FROM table2 RETURNING id
How can I do it?
DBMS is PostgreSQL
with inserted as (
INSERT INTO table1 (value1,value2)
SELECT value3,value4
FROM table2
RETURNING id
)
insert into temp
select id
from inserted;
This requires Postgres 9.2 or later.
Two options.
If you need it just for one follow-up query, a with statement (see the horse's answer) is the easiest.
If you need it for more than one follow-up query, the other option is to not use insert ... returning, but rather create table as:
CREATE TEMPORARY TABLE foo AS
SELECT value3,value4 FROM table2
Caveats: if necessary, create the indexes you need on the table -- and analyze it if you do.

Insert contents from #Temp table into real table

I have a temp table where i have changed some values in the database and am trying to nsert these back into the real table but it is not working I have this below:
SELECT * INTO dbo.PackageProduct FROM #PackageP
where #PackageP is my temp table
I am getting this error after the second run:
There is already an object named 'PackageProduct' in the database.
If the table already exists you have to use INSERT as SELECT...INTO creates a new table:
INSERT dbo.PackageProduct (<columns...>)
SELECT (<columns...>) FROM #PackageP
TRY
INSERT INTO dbo.PackageProduct SELECT * FROM #PackageP
Assuming you've got the same number and order of columns in both tables try this:
INSERT INTO dbo.PackageProduct
SELECT *
FROM #PackageP
If you do select * into ... it will create a table, if the same name already exist then it will show error, and the error clearly identifies that there is already a object (table/view/proc... ) in the database. check with some other name or check the existing object is not required then drop it and then use your query or insert it into the table(if both your temp table and the existing object structure is same and it is a table).

Hive insert query like SQL

I am new to hive, and want to know if there is anyway to insert data into Hive table like we do in SQL. I want to insert my data into hive like
INSERT INTO tablename VALUES (value1,value2..)
I have read that you can load the data from a file to hive table or you can import data from one table to hive table but is there any way to append the data as in SQL?
Some of the answers here are out of date as of Hive 0.14
https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DML#LanguageManualDML-InsertingvaluesintotablesfromSQL
It is now possible to insert using syntax such as:
CREATE TABLE students (name VARCHAR(64), age INT, gpa DECIMAL(3, 2));
INSERT INTO TABLE students
VALUES ('fred flintstone', 35, 1.28), ('barney rubble', 32, 2.32);
You can use the table generating function stack to insert literal values into a table.
First you need a dummy table which contains only one line. You can generate it with the help of limit.
CREATE TABLE one AS
SELECT 1 AS one
FROM any_table_in_your_database
LIMIT 1;
Now you can create a new table with literal values like this:
CREATE TABLE my_table AS
SELECT stack(3
, "row1", 1
, "row2", 2
, "row3", 3
) AS (column1, column2)
FROM one
;
The first argument of stack is the number of rows you are generating.
You can also add values to an existing table:
INSERT INTO TABLE my_table
SELECT stack(2
, "row4", 1
, "row5", 2
) AS (column1, column2)
FROM one
;
Slightly better version of the unique2 suggestion is below:
insert overwrite table target_table
select * from
(
select stack(
3, # generating new table with 3 records
'John', 80, # record_1
'Bill', 61 # record_2
'Martha', 101 # record_3
)
) s;
Which does not require the hack with using an already exiting table.
You can use below approach. With this, You don't need to create temp table OR txt/csv file for further select and load respectively.
INSERT INTO TABLE tablename SELECT value1,value2 FROM tempTable_with_atleast_one_records LIMIT 1.
Where tempTable_with_atleast_one_records is any table with atleast one record.
But problem with this approach is that If you have INSERT statement which inserts multiple rows like below one.
INSERT INTO yourTable values (1 , 'value1') , (2 , 'value2') , (3 , 'value3') ;
Then, You need to have separate INSERT hive statement for each rows. See below.
INSERT INTO TABLE yourTable SELECT 1 , 'value1' FROM tempTable_with_atleast_one_records LIMIT 1;
INSERT INTO TABLE yourTable SELECT 2 , 'value2' FROM tempTable_with_atleast_one_records LIMIT 1;
INSERT INTO TABLE yourTable SELECT 3 , 'value3' FROM tempTable_with_atleast_one_records LIMIT 1;
No. This INSERT INTO tablename VALUES (x,y,z) syntax is currently not supported in Hive.
You could definitely append data into an existing table. (But it is actually not an append at the HDFS level). It's just that whenever you do a LOAD or INSERT operation on an existing Hive table without OVERWRITE clause the new data will be put without replacing the old data. A new file will be created for this newly inserted data inside the directory corresponding to that table. For example :
I have a file named demo.txt which has 2 lines :
ABC
XYZ
Create a table and load this file into it
hive> create table demo(foo string);
hive> load data inpath '/demo.txt' into table demo;
Now,if I do a SELECT on this table it'll give me :
hive> select * from demo;
OK
ABC
XYZ
Suppose, I have one more file named demo2.txt which has :
PQR
And I do a LOAD again on this table without using overwrite,
hive> load data inpath '/demo2.txt' into table demo;
Now, if I do a SELECT now, it'll give me,
hive> select * from demo;
OK
ABC
XYZ
PQR
HTH
Ways to insert data into Hive table:
for demonstration, I am using table name as table1 and table2
create table table2 as select * from table1 where 1=1;
or
create table table2 as select * from table1;
insert overwrite table table2 select * from table1;
--it will insert data from one to another. Note: It will refresh the target.
insert into table table2 select * from table1;
--it will insert data from one to another. Note: It will append into the target.
load data local inpath 'local_path' overwrite into table table1;
--it will load data from local into the target table and also refresh the target table.
load data inpath 'hdfs_path' overwrite into table table1;
--it will load data from hdfs location iand also refresh the target table.
or
create table table2(
col1 string,
col2 string,
col3 string)
row format delimited fields terminated by ','
location 'hdfs_location';
load data local inpath 'local_path' into table table1;
--it will load data from local and also append into the target table.
load data inpath 'hdfs_path' into table table1;
--it will load data from hdfs location and also append into the target table.
insert into table2 values('aa','bb','cc');
--Lets say table2 have 3 columns only.
Multiple insertion into hive table
Yes you can insert but not as similar to SQL.
In SQL we can insert the row level data, but here you can insert by fields (columns).
During this you have to make sure target table and the query should have same datatype and same number of columns.
eg:
CREATE TABLE test(stu_name STRING,stu_id INT,stu_marks INT)
ROW FORMAT DELIMITED
FIELDS TERMINATED BY ','
STORED AS TEXTFILE;
INSERT OVERWRITE TABLE test SELECT lang_name, lang_id, lang_legacy_id FROM export_table;
To insert entire data of table2 in table1. Below is a query:
INSERT INTO TABLE table1 SELECT * FROM table2;
You can't do insert into to insert single record. It's not supported by Hive. You may place all new records that you want to insert in a file and load that file into a temp table in Hive. Then using insert overwrite..select command insert those rows into a new partition of your main Hive table. The constraint here is your main table will have to be pre partitioned. If you don't use partition then your whole table will be replaced with these new records.
Enter the following command to insert data into the testlog table with some condition:
INSERT INTO TABLE testlog SELECT * FROM table1 WHERE some condition;
I think in such scenarios you should be using HBASE which facilitates such kind of insertion but it does not provide any SQL kind of query language. You need you use Java API of HBASE like the put method to do such kind of insertion. Moreover HBASE is column oriented no-sql database.
You still can insert into complex type in Hive - it works
(id is int, colleagues array)
insert into emp (id,colleagues) select 11, array('Alex','Jian') from (select '1')
you can add values to specific columns as well, just specify the column names in which you like to add corresponding values:
Insert into Table (Col1, Col2, Col4,col5,Col7) Values ('Va11','Va2','Val4','Val5','Val7');
Make sure the columns you skip dont have not null value type.
There are few properties to set to make a Hive table support ACID properties and to insert the values into tables as like in SQL .
Conditions to create a ACID table in Hive.
The table should be stored as ORC file. Only ORC format can support ACID prpoperties for now.
The table must be bucketed
Properties to set to create ACID table:
set hive.support.concurrency =true;
set hive.enforce.bucketing =true;
set hive.exec.dynamic.partition.mode =nonstrict
set hive.compactor.initiator.on = true;
set hive.compactor.worker.threads= 1;
set hive.txn.manager = org.apache.hadoop.hive.ql.lockmgr.DbTxnManager;
set the property hive.in.test to true in hive.site.xml
After setting all these properties , the table should be created with tblproperty 'transactional' ='true'. The table should be bucketed and saved as orc
CREATE TABLE table_name (col1 int,col2 string, col3 int) CLUSTERED BY col1 INTO 4
BUCKETS STORED AS orc tblproperties('transactional' ='true');
Now its possible to inserte values into the table like SQL query.
INSERT INTO TABLE table_name VALUES (1,'a',100),(2,'b',200),(3,'c',300);
Yes we can use Insert query in Hive.
hive> create table test (id int, name string);
INSERT: INSERT...VALUES is available starting in version 0.14.
hive> insert into table test values (1,'mytest');
This is going to work for insert. We have to use values keyword.
Note: User cannot insert data into a complex datatype column (array, map, struct, union) using the INSERT INTO...VALUES clause.

Temporary tables and AS statement usage

If I have a query, say:
SELECT *
FROM ( SELECT fields
FROM tables
WHERE condition
)
AS TEMP_TABLE
are the results of the above query saved in a temporary table called TEMP_TABLE so as I can perform another query on it later? Will the query below be executed successfully when using DB2?
SELECT fields
FROM TEMP_TABLE
WHERE condition
The answer is NO, it's just an alias for a subquery.
If you want to use it later, you have to explicitly create it.
you can create temporary table in following way.
CREATE TEMPORARY TABLE temp_table AS (
SELECT fields
FROM tables
WHERE condition
);
then you can retrieve data from the temp table as below.
SELECT * FROM temp_table

In MySQL, how to copy the content of one table to another table within the same database?

I am new to MySQL. I would like to copy the content of one table to another table within the same database. Basically, I would like to insert to a table from another table. Is there easy way of doing this?
If the tables have the same structure:
INSERT INTO TARGET_TABLE SELECT * FROM SOURCE_TABLE;
If the tables have different structures:
INSERT INTO TARGET_TABLE (`col1`,`col2`) SELECT `col1`,`col2` FROM SOURCE_TABLE;
You can also add conditions:
INSERT INTO TARGET_TABLE (`col1_`,`col2_`) SELECT `col1`,`col2` FROM SOURCE_TABLE WHERE `foo`=1
If the table doesn't exist, you can create one with the same schema like so:
CREATE TABLE table2 LIKE table1;
Then, to copy the data over:
INSERT INTO table2 SELECT * FROM table1
If table1 is large and you don't want to lock it for the duration of the copy process, you can do a dump-and-load instead:
CREATE TABLE table2 LIKE table1;
SELECT * INTO OUTFILE '/tmp/table1.txt' FROM table1;
LOAD DATA INFILE '/tmp/table1.txt' INTO TABLE table2;
This worked for me,
CREATE TABLE newtable LIKE oldtable;
Replicates newtable with old table
INSERT newtable SELECT * FROM oldtable;
Copies all the row data to new table.
If you want to create and copy the content in a single shot, just use the SELECT:
CREATE TABLE new_tbl SELECT * FROM orig_tbl;
This worked for me. You can make the SELECT statement more complex, with WHERE and LIMIT clauses.
First duplicate your large table (without the data), run the following query, and then truncate the larger table.
INSERT INTO table_small (SELECT * FROM table_large WHERE column = 'value' LIMIT 100)
Super simple. :-)
CREATE TABLE target_table SELECT * FROM source_table;
It just create a new table with same structure as of source table and also copy all rows from source_table into target_table.
CREATE TABLE target_table SELECT * FROM source_table WHERE condition;
If you need some rows to be copied into target_table, then apply a condition inside where clause
Try this. Works well in my Oracle 10g,
CREATE TABLE new_table
AS (SELECT * FROM old_table);