If I have a SQL table with columns:
NR_A, NR_B, NR_C, NR_D, R_A, R_B, R_C
and on runtime, I add columns following the column's sequence such that the next column above would be R_D followed by R_E.
My problem is I need to reset the values of columns that starts with R_ (labeled that way to indicate that it is resettable) back to 0 each time I re-run my script . NR_ columns btw are fixed, so it is simpler to just say something like:
UPDATE table set col = 0 where column name starts with 'NR_'
I know that is not a valid SQL but I think its the best way to state my problem.
Any thoughts?
EDIT: btw, I use postgres (if that would help) and java.
SQL doesn't support dynamically named columns or tables--your options are:
statically define column references
use dynamic SQL to generate & execute the query/queries
Java PreparedStatements do not insulate you from this--they have the same issue, just in Java.
Are you sure you have to add columns during normal operations? Dynamic datamodels are most of the time a realy bad idea. You will see locking and performance problems.
If you need a dynamic datamodel, take a look at key-value storage. PostgreSQL also has the extension hstore, check the contrib.
If you don't have many columns and you don't expect the schema to change, just list them explicitly.
UPDATE table SET NR_A=0;
UPDATE table SET NR_B=0;
UPDATE table SET NR_C=0;
UPDATE table SET NR_D=0;
Otherwise, a simple php script could dynamically build and execute your query:
<?php
$db = pg_connect("host=localhost port=5432 user=postgres password=mypass dbname=mydb");
if(!$db) die("Failed to connect");
$reset_cols = ["A","B","C","D"];
foreach ($col in $reset_cols) {
$sql = "UPDATE my_table SET NR_" . $col . "=0";
pg_query($db,$sql);
}
?>
You could also lookup table's columns in Postgresql by querying the information schema columns tables, but you'll likely need to write a plpgsql function to loop over the query results (one row per table column starting with "NR_").
if you rather using sql query script, you should try to get the all column based on given tablename.
maybe you could try this query to get all column based on given tablename to use in your query.
SELECT attname FROM
pg_attribute, pg_type
WHERE typname = 'tablename' --your table name
AND attrelid = typrelid
AND attname NOT IN ('cmin', 'cmax', 'ctid', 'oid', 'tableoid', 'xmin', 'xmax')
--note that this attname is sys column
the query would return all column with given tablename except system column
Related
I need to know the list of the column and values from the update sql using java. Code is to read a update query and take backup of the actual column values before executing the update sql. For this is need to know the column names. Please advise!
sql = update testenv.employee set gender = '2',StudentInd = '112233' where empID in (987987);
String criteriaQuery = resultset.getString("query"); // this is the update statement which is not constant and varies everytime.
String schema = StringUtils.substringBetween(criteriaQuery.toUpperCase(), "UPDATE ", ".").trim();
String table = StringUtils.substringBetween(criteriaQuery.toUpperCase(), ".", "SET").trim();
String columnName = StringUtils.substringBetween(criteriaQuery.toUpperCase(), "SET", "=").trim();
But columnName will not get the correct columns. Need to optimise the code such that i can get the entire column names from the update query.
If you're using JDBC, you can use the following:
ResultSetMetaData md = rs.getMetaData();
after getting the result set of your select statement.
http://www.roseindia.net/jdbc/jdbc-mysql/DiscriptionTable.shtml
Provides a clear example, the same applies for SQLServer databases and Oracle.
I'm tring to create a table in mysql from java desktop program but I obtain a MySqlSyntaxErrorException.
The query is :
CREATE TABLE FileXFascia(fila0 Integer,fila1 Integer,fila2 Integer,fila3 Integer) VALUES ('3','4','3','3')
Anyone knows where I'm wrong?
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'VALUES ('3','4','3','3')' at line 1
You need to split these as follows:
CREATE TABLE FileXFascia(fila0 Integer,fila1 Integer,fila2 Integer,fila3 Integer);
INSERT INTO FileXFascial (fila0, fila1, fila2, fila3) VALUES ('3','4','3','3');
In your question there are two different operations on a table, You are trying to create and insert data in single query even in a wrong way. First you need to create table then insert data into created table. Like below syntax.
create table tableName(col1 dataType,col2 dataType,col3 dataType,.......coln dataType);
After creation of table now you can insert data into table. Like below syntax.
insert into tableName(col1, col2,col3,......coln) values ('data1','data2','data3',......'datan');
With jooq 3.4 I can't figure out how to do this (with Postgresql):
Query query = dsl.insertInto(TABLE)
.set(TABLE.ID, Sequences.TABLE_ID_SEQ.nextval());
but in a case when I don't know which is the exact table, something like this:
TableImpl<?> tableImpl;
Query query = dsl.insertInto(tableImpl)
.set(tableImpl.getIdentity(), tableImpl.getIdentity().getSequence().nextval());
Is it somehow possible?
I tried this:
dsl.insertInto(tableImpl)
.set(DSL.field("id"),
tableImpl.getSchema().getSequence("table_id_seq").nextval())
This works but I still don't know how to get the sequence name from the TableImpl object.
Is there a solution for this? Or is there a problem with my approach?
In plain SQL I would do this:
insert into table_A (id) VALUES nextval('table_A_id_seq');
insert into table_B (table_A_id, some_val) VALUES (currval('table_A_id_seq'), some_val);
So I need the value or a reference to that id for later use of the id that was generated for the inserted record as default, but I don't want to set any other values.
jOOQ currently doesn't have any means of associating a table with its implicitly used sequence for the identity column. The reason for this is that the sequence is generated when the table is created, but it isn't formally connected to that table.
Usually, you don't have to explicitly set the serial value of a column in a PostgreSQL database. It is generated automatically on insert. In terms of DDL, this means:
CREATE TABLE tablename (
colname SERIAL
);
is equivalent to specifying:
CREATE SEQUENCE tablename_colname_seq;
CREATE TABLE tablename (
colname integer NOT NULL DEFAULT nextval('tablename_colname_seq')
);
ALTER SEQUENCE tablename_colname_seq OWNED BY tablename.colname;
The above is taken from:
http://www.postgresql.org/docs/9.3/static/datatype-numeric.html#DATATYPE-SERIAL
In other words, just leave out the ID values from the INSERT statements.
"Empty" INSERT statements
Note that if you want to create an "empty" INSERT statement, i.e. a statement where you pass no values at all, generating a new column with a generated ID, you can use the DEFAULT VALUES clause.
With SQL
INSERT INTO tablename DEFAULT VALUES
With jOOQ
DSL.using(configuration)
.insertInto(TABLENAME)
.defaultValues()
.execute();
Returning IDs
Note that PostgreSQL has native support for an INSERT .. RETURNING clause, which is also supported by jOOQ:
With SQL
INSERT INTO tablename (...) VALUES (...) RETURNING ID
With jOOQ
DSL.using(configuration)
.insertInto(TABLENAME, ...)
.values(...)
.returning(TABLENAME.ID)
.fetchOne();
I am trying to setup a query for my application to pull only values from a table that have a specific column set. Mostly this column will be null, but if you edit and save the item on the application end without putting anything in this field, then it saves a blank string to that database field.
I have tried the TSQL query:
SELECT * from TABLE where COLUMN is not NULL AND COLUMN != ''
This query returns the results I need, but when I run the same query in HQL:
SELECT OBJECT from TABLE where COLUMN is not NULL and COLUMN <> ''
Then it still contains the values that have a blank string in that column. I have tried this using HQL with the operators <> and !=, and have also tried converting it to a criteria object using Restrictions.ne("column","") but nothing seems to provide the result I need.
I tried Length as in the comments, but had no luck. With the length in the query hibernate generates the full query as so. the time_clock_id column is the one that i'm having the problem with. Hibernate is set to SQLServerDialect
select timezone0_.time_zone_id as time1_368_, timezone0_.version as version368_, timezone0_.modification_timestamp as modifica3_368_, timezone0_.time_offset as time4_368_, timezone0_.modification_user as modifica5_368_, timezone0_.name as name368_, timezone0_.description as descript7_368_, timezone0_.active as active368_, timezone0_.time_clock_id as time9_368_ from time_zone timezone0_ where timezone0_.active=1 and (timezone0_.time_clock_id is not null) and len(timezone0_.time_clock_id)>0
Rookie Mistake. There was another place within my action class where I was using a different query to build the select list in the application. This was resulting in the list being overwritten with all values instead of those that use blank. After snipping this duplication I can use the operator column <> '' and I am getting the correct results
In MySQL, if you specify ON DUPLICATE KEY UPDATE and a row is inserted that would cause a duplicate value in a UNIQUE index or PRIMARY KEY, an UPDATE of the old row is performed. For example, if column a is declared as UNIQUE and contains the value 1, the following two statements have identical effect:
INSERT INTO table (a,b,c) VALUES (1,2,3)
ON DUPLICATE KEY UPDATE c=c+1;
UPDATE table SET c=c+1 WHERE a=1;
I don't believe I've come across anything of the like in T-SQL. Does SQL Server offer anything comparable to MySQL's ON DUPLICATE KEY UPDATE?
I was surprised that none of the answers on this page contained an example of an actual query, so here you go:
A more complex example of inserting data and then handling duplicate
MERGE
INTO MyBigDB.dbo.METER_DATA WITH (HOLDLOCK) AS target
USING (SELECT
77748 AS rtu_id
,'12B096876' AS meter_id
,56112 AS meter_reading
,'20150602 00:20:11' AS time_local) AS source
(rtu_id, meter_id, meter_reading, time_local)
ON (target.rtu_id = source.rtu_id
AND target.time_local = source.time_local)
WHEN MATCHED
THEN UPDATE
SET meter_id = '12B096876'
,meter_reading = 56112
WHEN NOT MATCHED
THEN INSERT (rtu_id, meter_id, meter_reading, time_local)
VALUES (77748, '12B096876', 56112, '20150602 00:20:11');
There's no DUPLICATE KEY UPDATE equivalent, but MERGE and WHEN MATCHED might work for you
Inserting, Updating, and Deleting Data by Using MERGE
You can try the other way around. It does the same thing more or less.
UPDATE tablename
SET field1 = 'Test1',
field2 = 'Test2'
WHERE id = 1
IF ##ROWCOUNT = 0
INSERT INTO tablename
(id,
field1,
field2)
VALUES (1,
'Test1',
'Test2')
SQL Server 2008 has this feature, as part of TSQL.
See documentation on MERGE statement here - http://msdn.microsoft.com/en-us/library/bb510625.aspx
SQL server 2000 onwards has a concept of instead of triggers, which can accomplish the wanted functionality - although there will be a nasty trigger hiding behind the scenes.
Check the section "Insert or update?"
http://msdn.microsoft.com/en-us/library/aa224818(SQL.80).aspx