I`m trying to insert some data into sqflite table but there is an error while executing insert query
await db.execute(
'CREATE TABLE $catrgoryTable($category_id INTEGER PRIMARY KEY UNIQUE , $colDeviceTypeId INTEGER, '
'$room_id INTEGER)');
print('category created!');
and here is the Error
SqfliteDatabaseException (DatabaseException(UNIQUE constraint failed: category_Table.category_id (code 1555)) sql 'INSERT INTO category_Table (category_id, device_type_id, room_id) VALUES (?, ?, ?)' args [1, 1, 1]})
Thanks for any help:)
The table category_Table has a unique constraint field on it, the error shows that you tried to enter a value for category_id that it already exists, which violates primary key's uniqueness constraint for this field. Only one row can exist with a given ID value. So If you're trying to insert a row, be sure that your category_id have a unique value, or if you don't care about generating ids by yourself, you can add AUTOINCREMENT setting to your category_id column definition. This way it will be filled automatically and each row will have its own unique value.
static Future<void> insert(String table, Map<String, dynamic> data) async {
final db = await DBHelper.database();
db.insert(table, data, conflictAlgorithm: sql.ConflictAlgorithm.replace);
}
here is my code is thought if I use conflict algorithm replace it would replace that unique value ?
In the insert function of database. Add
conflictAlgorithm: ConflictAlgorithm.replace.
it worked for me
Related
This is a small part of the data in my table PLANT I'm having in database...
id name code
123 OFFICE1 A1234
456 OFFICE2 B4567
789 OFFICE3 C8989
When I get all the data from an api, before inserting them into the database, I want to check if any records are present already.
This is how I'm checking if a record is present..
let isExists = sharedInstance.plantExists(thePlantObject, id: 123)
func plantExists(_ items: plant,id: Int) -> Bool {
var isExists = false
sharedInstance.database!.open()
isExists = sharedInstance.database!.executeUpdate("EXISTS(SELECT * FROM PLANT WHERE PLANT.id = ?)", withArgumentsIn: [id])
sharedInstance.database!.close()
return isExists
}
But if I print isExists, then this message is printed... (Bool) isExists = <variable not available>
What am I doing wrong here..?
If you can change the schema of db then make sure id attribute is set as unique and insertion will fail if you are inserting id which already exists in the column.
Or Just do select query with id and see if any results come back to you
Select * from where id =
As per comment #Joakim Danielson, EXISTS should be a part of WHERE clause.
You can achieve it feature two way
1. The way you are approaching (checking existence and based on that insert).
Instead of using EXISTS use following query
SELECT COUNT(id) FROM PLANT WHERE PLANT.id = ?
This way you can get the count of specific id. Here i assume that you didn't put any UNIQUE constraints in id column. If you set UNIQUE constraint in id column, then second approach is the best approach for you.
2. Let the SQLite handle itself (based on a constraint)
While create the db schema, make the id unique. Assumed schema creation query is following
CREATE TABLE plant (
id INT(11) UNIQUE NOT NULL,
name VARCHAR(255)
);
use following query while inserting
INSERT OR IGNORE (`id`, `name`) VALUES (?, ?)
This way, it will ignore inserting if any sort of constraint fails.
Working demo is here.
NB: It won't report any failure.
I have created two tables in Snowflake.
create or replace TRANSIENT TABLE TESTPARENT (
COL1 NUMBER(38,0) NOT NULL,
COL2 VARCHAR(16777216) NOT NULL,
COL3 VARCHAR(16777216) NOT NULL,
constraint UNIQ_COL3 unique (COL3)
);
create or replace TRANSIENT TABLE TESTCHILD3 (
COL_A NUMBER(38,0) NOT NULL,
COL_B NUMBER(38,0) NOT NULL,
ABCDEF VARCHAR(16777216) NOT NULL,
constraint FKEY_1 foreign key (COL_A, COL_B) references TEST_DB.PUBLIC.TESTPARENT1(COL1,COL2),
constraint FKEY_2 foreign key (ABCDEF) references TEST_DB.PUBLIC.TESTPARENT(COL3)
);
Now I want to execute a query and see the names of columns that are involved in FKEY_2 FOREIGN KEY
in Table TESTCHILD3, but it seems like there are no DB Table/View that keeps this information. I can find out the column names for UNIQUE KEY & PRIMARY KEY but there is nothing for FOREIGN KEYS.
EDIT
I have already tried INFORMATION_SCHEMA.TABLE_CONSTRAINTS, along with INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS and all the other system tables. No luck. Only DESC TABLE is giving me some info related to CONSTRAINTS and COLUMNS but that also has FOREIGN KEY CONSTRAINTS information missing.
SHOW IMPORTED KEYS IN TABLE <fk_table_name>;
Updated answer:
I was checking on something unrelated and noticed a very efficient way to list all primary and foreign keys:
show exported keys in account; -- Foreign keys
show primary keys in account;
When you limit the call to a table, it appears you have to request the foreign keys that point to the parent table:
show exported keys in table "DB_NAME"."SCHEMA_NAME"."PARENT_TABLE";
You can check the documentation for how to limit the show command to a specific database or schema, but this returns rich information in a table very quickly.
maybe you can try to query this view: INFORMATION_SCHEMA.TABLE_CONSTRAINTS
Note: TABLE_CONSTRAINTS only displays objects for which the current role for the session has been granted access privileges.
For more see: https://docs.snowflake.net/manuals/sql-reference/info-schema/table_constraints.html
I am constantly receiving DB error NO Column found inspite i have recreated column and verified it too many times.
Below is the table structure:
CREATE TABLE "ContractorTester" ("ContrTestID" VARCHAR NOT NULL ,"Ack" VARCHAR NOT NULL ,"TesterLName" VARCHAR,"TesterFName" VARCHAR,"GaugeName1" VARCHAR,"GaugeMake1" VARCHAR,"TestCrossConLic" VARCHAR,"CCLicExpDate" VARCHAR,"GaugeSerialNum1" VARCHAR,"GaugeCalibrDate1" VARCHAR,"ContrCompanyName1" VARCHAR,"ContrAddr1" VARCHAR,"ContrCity1" VARCHAR,"ContrState1" VARCHAR,"ContrZip1" VARCHAR,"ContrPhone1" VARCHAR,"Lat" DOUBLE,"Log" DOUBLE,"MCreatedDate" VARCHAR,"MUpdatedDate" VARCHAR,"ActLocalCT
" VARCHAR,"ContrTestTranID" VARCHAR PRIMARY KEY )
Below is Insert Query:
INSERT OR REPLACE INTO ContractorTester ('GaugeName1','GaugeMake1','ContrPhone1','ContrTestTranID','TesterFName','ContrAddr1','ContrCity1','ContrZip1','CCLicExpDate','TestCrossConLic','GaugeCalibrDate1','Ack','TesterLName','ContrTestID','ContrState1','ContrCompanyName1','GaugeSerialNum1','ActLocalCT','Log','Lat') VALUES ('TK-99F','MIDWEST','(847) 111-3314','0','Jack','819 Main1','Lake Zurich','60051','2016-04-17T00:00:00.003','XC3673','2015-04-17T00:00:00.003','0','Skirm','5','IL','American Backflow Prevention Inc.','TG0605','1','0','0')
Below is the error:
SQLiteManager: Likely SQL syntax error: INSERT OR REPLACE INTO ContractorTester ('GaugeName1','GaugeMake1','ContrPhone1','ContrTestTranID','TesterFName','ContrAddr1','ContrCity1','ContrZip1','CCLicExpDate','TestCrossConLic','GaugeCalibrDate1','Ack','TesterLName','ContrTestID','ContrState1','ContrCompanyName1','GaugeSerialNum1','ActLocalCT','Log','Lat') VALUES ('TK-99F','MIDWEST','(847) 111-3314','0','Jack','819 Main1','Lake Zurich','60051','2016-04-17T00:00:00.003','XC3673','2015-04-17T00:00:00.003','0','Skirm','5','IL','American Backflow Prevention Inc.','TG0605','1','0','0') [ table ContractorTester has no column named ActLocalCT ]
Exception Name: NS_ERROR_FAILURE
Exception Message: Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [mozIStorageConnection.createStatement]
Please any one review and let me know what is the wrong in above Queries.
Thanks in advance.
Replace
INSERT OR REPLACE INTO ContractorTester
with
INSERT OR REPLACE INTO ContractorTester VALUES
Without the VALUES the list in parens is the list of columns to insert into, not the list of values to insert.
I have a mysql DB with rails, and a column "shorthand" (string) that I'd like to make unique across multiple tables. Is there a way I can do this without making a third table?
Expression
id
shorthand
...
etc
Variable
id
shorthand
...
etc
I want the values in the 'shorthand' columns of both tables to be unique between each other ie. a record shorthand value "xyz" in Expression would be rejected if a Variable with shorthand value "xyz" were to exist in the DB already.
Any thoughts appreciated, even "you have to use a third table" :)
Here an example using a third table:
-- TEMP SCHEMA for testing
DROP SCHEMA tmp CASCADE;
CREATE SCHEMA tmp ;
SET search_path=tmp;
CREATE TABLE shorthand
( shorthand varchar NOT NULL PRIMARY KEY
, one_or_two varchar NOT NULL
);
CREATE TABLE table_one
( one_id INTEGER NOT NULL PRIMARY KEY
, shorthand varchar NOT NULL REFERENCES shorthand(shorthand)
ON DELETE CASCADE ON UPDATE CASCADE
DEFERRABLE INITIALLY DEFERRED
, etc_one varchar
);
CREATE TABLE table_two
( two_id INTEGER NOT NULL PRIMARY KEY
, shorthand varchar NOT NULL REFERENCES shorthand(shorthand)
ON DELETE CASCADE ON UPDATE CASCADE
DEFERRABLE INITIALLY DEFERRED
, etc_two varchar
);
-- Trigger function for BOTH tables
CREATE FUNCTION set_one_or_two( ) RETURNS TRIGGER
AS $func$
BEGIN
IF (TG_OP = 'INSERT') THEN
INSERT INTO shorthand (shorthand, one_or_two)
VALUES(new.shorthand, TG_TABLE_NAME)
;
ELSEIF (TG_OP = 'UPDATE') THEN
UPDATE shorthand SET shorthand = new.shorthand
WHERE shorthand = old.shorthand
;
ELSEIF (TG_OP = 'DELETE') THEN
DELETE FROM shorthand
WHERE shorthand = old.shorthand
;
END IF;
RETURN NULL;
END
$func$ LANGUAGE plpgsql
;
-- Triggers for I/U/D
CREATE CONSTRAINT TRIGGER check_one
AFTER INSERT OR UPDATE OR DELETE
ON table_one
FOR EACH ROW
EXECUTE PROCEDURE set_one_or_two ( )
;
CREATE CONSTRAINT TRIGGER check_two
AFTER INSERT OR UPDATE OR DELETE
ON table_two
FOR EACH ROW
EXECUTE PROCEDURE set_one_or_two ( )
;
-- Some tests (incomplete)
INSERT INTO table_one (one_id,shorthand,etc_one) VALUES (1, 'one' , 'one' );
INSERT INTO table_two (two_id,shorthand,etc_two) VALUES (1, 'two' , 'two' );
SELECT * FROM shorthand;
\echo this should fail
INSERT INTO table_one (one_id,shorthand,etc_one) VALUES (11, 'two' , 'eleven' );
SELECT * FROM shorthand;
UPDATE table_one SET shorthand = 'eleven' WHERE one_id = 1;
SELECT * FROM shorthand;
I think this older article does exactly what you are looking for (simulating multi table constraints):
http://classes.soe.ucsc.edu/cmps180/Winter04/constraints.html
You might also like to investigate postgres CREATE CONSTRAINT TRIGGER using a function similar to the check_nojoin() function in the article.
http://www.postgresql.org/docs/9.0/static/sql-createconstraint.html
Once you have the exact SQL you need you can put it in your rails migration with execute "the required SQL"
An alternative approach is to use a third table 'shorthands' with columns 'shorthand' and 'src'. Define shorthand as the unique primary key on that table. On each of your other two tables define 'src' as a single char field defaulting to 'A' and 'B' on each table respecitively. Add a foreign key constraint on each of your two tables consisting of both 'shorthand' and 'src' and referencing table 'shorthands'. When inserting or updating rows in either of your two tables you need to ensure the 'shorthands' table is updated either explicity as part of your transaction or via a trigger and set both 'shorthand', and 'src' to the respective table ie 'A' or 'B'.
What the foreign key constraints do is ensure that the shorthand value exists in the shorthand's table for the respective src table but because of the uniqueness constraint on just the 'shorthand' column in the shorthand's table if the other table has already defined the shorthand value a key violation will occur thus guaranteeing uniqueness across two (or even more) tables.
Whatever you do, it is best to put the referential integrity into the database, not in orm/active record validations.
I have a column with the type of Varchar in my Postgres database which I meant to be integers... and now I want to change them, unfortunately this doesn't seem to work using my rails migration.
change_column :table1, :columnB, :integer
Which seems to output this SQL:
ALTER TABLE table1 ALTER COLUMN columnB TYPE integer
So I tried doing this:
execute 'ALTER TABLE table1 ALTER COLUMN columnB TYPE integer USING CAST(columnB AS INTEGER)'
but cast doesn't work in this instance because some of the column are null...
any ideas?
Error:
PGError: ERROR: invalid input syntax for integer: ""
: ALTER TABLE table1 ALTER COLUMN columnB TYPE integer USING CAST(columnB AS INTEGER)
Postgres v8.3
It sounds like the problem is that you have empty strings in your table. You'll need to handle those, probably with a case statement, such as:
execute %{ALTER TABLE "table1" ALTER COLUMN columnB TYPE integer USING CAST(CASE columnB WHEN '' THEN NULL ELSE columnB END AS INTEGER)}
Update: completely rewritten based on updated question.
NULLs shouldnt be a problem here.
Tell us your postgresql version and your error message.
Besides, why are you quoting identifiers ? Be aware that unquoted identifiers are converted to lowercase (default behaviour), so there might be a problem with your "columnB" in your query - it appears quoted first, unquoted in the cast.
Update: Before converting a column to integer, you must be sure that all you values are convertible. In this case, it means that columnB should contains only digits (or null).
You can check this by something like
select columnB from table where not columnB ~ E'^[0-9]+$';
If you want your empty strings to be converted to NULL integers, then run first
UPDATE table set columnB = NULL WHERE columnB = '';