how to get the primary key value after the tablename.Save() method
For Example:
Table.Save();
here how to my auto generated primary key value...
There's a couple of ways. You can just check the primary key property, so if you Table has an auto incrementing integer primary key you could do:
int primaryKeyValue = Table.Id;
Or you could use the KeyValue() method, which returns an object:
object primaryKeyValue = Table.KeyValue();
Related
Im currently working on creating correct database columns for my database. I have created two tables and used alter:
CREATE TABLE stores (
id SERIAL PRIMARY KEY,
store_name TEXT
-- add more fields if needed
);
CREATE TABLE products (
id SERIAL,
store_id INTEGER NOT NULL,
title TEXT,
image TEXT,
url TEXT UNIQUE,
added_date timestamp without time zone NOT NULL DEFAULT NOW(),
PRIMARY KEY(id, store_id)
);
ALTER TABLE products
ADD CONSTRAINT "FK_products_stores" FOREIGN KEY ("store_id")
REFERENCES stores (id) MATCH SIMPLE
ON UPDATE NO ACTION
ON DELETE RESTRICT;
Now I am trying to use it together with PeeWee and I have managed to do a small step which is:
class Stores(Model):
id = IntegerField(column_name='id')
store_id = TextField(column_name='store_name')
class Products(Model):
id = IntegerField(column_name='id')
store_id = IntegerField(column_name='store_id')
title = TextField(column_name='title')
url = TextField(column_name='url')
image = TextField(column_name='image')
However my problem is that I have used:
ALTER TABLE products
ADD CONSTRAINT "FK_products_stores" FOREIGN KEY ("store_id")
REFERENCES stores (id) MATCH SIMPLE
ON UPDATE NO ACTION
ON DELETE RESTRICT;
which means that I do have a Foreign key and I am quite not sure how I can apply to use Foreign key together with PeeWee. I wonder how can I do that?
You need to add a ForeignKeyField to Products and remove store_id
class Products(Model):
id = IntegerField(column_name='id')
title = TextField(column_name='title')
url = TextField(column_name='url')
image = TextField(column_name='image')
store = ForeignKeyField(Stores, backref='products')
I have an html table that is filled from a DynamoDB table. Clicking a row pops up an edit form in a modal. The data inputted is sent to a flask server to update the item - using AWS DynamoDB - that was edited in the modal form. Upon reading the AWS documentation for this, the correct method is to use update_item. However, when doing so the item is added again instead of updating the item. I used the AWS here to script the below. In my DynamoDB table, the primary partition key is KEY1 and the primary sort key is KEY2 in the below reference.
table = dynamodb.Table('table_name') #define DynamoDB table
key1 = account_id #string value of account id
key2 = request.form["KEY2"] #this is a read only field in the form, so the key does not get updated here
form_val1 = request.form["input1"]
form_val2 = request.form["input2"]
form_val3 = request.form["input3"]
form_val4 = request.form["input4"]
form_val5 = request.form["input5"]
form_val6 = request.form["input6"]
form_val7 = request.form["input7"]
form_val8 = request.form["input8"]
form_val9 = request.form["input9"]
#update item in dynamo
table.update_item(
Key={
'KEY1': key1, #partition key
'KEY2': key2 #sort key
},
UpdateExpression='SET dbField1 = :val1, dbField2 = :val2, dbField3 = :val3, dbField4 = :val4, dbField5 = :val5, dbField6 = :val6, dbField7 = :val7, dbField8 = :val8, dbField9 = :val9',
ExpressionAttributeValues={
':val1': form_val1,
':val2': form_val2,
':val3': form_val3,
':val4': form_val4,
':val5': form_val5,
':val6': form_val6,
':val7': form_val7,
':val8': form_val8,
':val9': form_val9
}
)
You can't and I will explain to you for what that not is possible.
When you create a table on dynamo DB with key and a order key you automatically create an index between key and sort key. We know an index is inmutable, that means you can't update the keys. Is for that reason that when you update dynamo create a new element.
It's a problem of the definition of your table because you never need to change the key or the sort key. Recreate your table only with the index and not with the sort index (because if your app can change the sort index that make not sense).
Is this the full query? the update_item docs say that TableName is required, which I don't see in your snippet.
From the updateitem docs:
Edits an existing item's attributes, or adds a new item to the table
if it does not already exist.
Make sure that the primary key (partition key and sort key) are unique in your table. If they are not, updateitem will create a new item in the database.
Are you absolutely certain that the primary key for the item already exists in the database?
Is there there any way to query on a SET type(or MAP/LIST) to find does it contain a value or not?
Something like this:
CREATE TABLE test.table_name(
id text,
ckk SET<INT>,
PRIMARY KEY((id))
);
Select * FROM table_name WHERE id = 1 AND ckk CONTAINS 4;
Is there any way to reach this query with YCQL api?
And can we use a SET type in SECONDRY INDEX?
Is there any way to reach this query with YCQL api?
YCQL does not support the CONTAINS keyword yet (feel free to open an issue for this on the YugabyteDB GitHub).
One workaround can be to use MAP<INT, BOOLEAN> instead of SET<INT> and the [] operator.
For instance:
CREATE TABLE test.table_name(
id text,
ckk MAP<int, boolean>,
PRIMARY KEY((id))
);
SELECT * FROM table_name WHERE id = 'foo' AND ckk[4] = true;
And can we use a SET type in SECONDRY INDEX?
Generally, collection types cannot be part of the primary key, or an index key.
However, "frozen" collections (i.e. collections serialized into a single value internally) can actually be part of either primary key or index key.
For instance:
CREATE TABLE table2(
id TEXT,
ckk FROZEN<SET<INT>>,
PRIMARY KEY((id))
) WITH transactions = {'enabled' : true};
CREATE INDEX table2_idx on table2(ckk);
Another option is to use with compound primary key and defining ckk as clustering key:
cqlsh> CREATE TABLE ybdemo.tt(id TEXT, ckk INT, PRIMARY KEY ((id), ckk)) WITH CLUSTERING ORDER BY (ckk DESC);
cqlsh> SELECT * FROM ybdemo.tt WHERE id='foo' AND ckk=4;
I am using Node with node-sqlite3. I cannot seem to delete rows by passing their primary key, but I can delete rows by passing some other column value.
Works
this.db.run("DELETE FROM MyTable WHERE Name = 'Bob'");
Does nothing
this.db.run("DELETE FROM MyTable WHERE _id = 3);
I have specified _id as my autoincrement / primary key. I can prove this by doing a PRAGMA and showing the debugger's results here, which clearly indicates _id as the pk
PRAGMA call
Debugger
I really don't know what to do as I get no errors from the db.run call
I have cassandra 2.1.15.
I have this table
CREATE TABLE ks_mobapp.messages (
pair_id text,
belong_to text,
message_id timeuuid,
cli_time bigint,
sender text,
text text,
time bigint,
PRIMARY KEY ((pair_id, belong_to), message_id)
) WITH CLUSTERING ORDER BY (message_id DESC)
I was trying to delete multiple record as
instances.getCqlSession().execute(QueryBuilder.delete()
.from(AppConstants.KEYSPACE, "messages")
.where(QueryBuilder.eq("pair_id", pairId))
.and(QueryBuilder.eq("belong_to", currentUser.value("userId")))
.and(QueryBuilder.in("message_id", msgId)));
I am getting error:
Caused by: com.datastax.driver.core.exceptions.InvalidQueryException: Invalid operator IN for PRIMARY KEY part message_id
Then I tried:
Session session = instances.getCqlSession();
PreparedStatement statement = session.prepare("DELETE FROM ks_mobApp.messages WHERE pair_id = ? AND belong_to = ? AND message_id = ?;");
Iterator<String> iterator = msgId.iterator();
while(iterator.hasNext()) {
try {
session.executeAsync(statement.bind(pairId, currentUser.value("userId"), UUID.fromString(iterator.next())));
} catch(Exception ex) {
}
}
Its working nice. Is this the correct way? I can't use IN for same partition key ?
DELETE in Query only supported for partition key.
Delete IN relation is only supported for partition key)
There are some WHERE clause restrictions for the UPDATE and DELETE statements in cassandra 2.x
more specifically you can only use the IN operator on the last partition key column. So in your case the last partition column is belong_to. so IN can only be used on that column.
However these limitation are removed in cassandra 3.0. and it will allow
IN to be specified on any partition key column
IN to be specified on any clustering column
Here is the patch https://issues.apache.org/jira/browse/CASSANDRA-6237
Read this also http://www.datastax.com/dev/blog/a-deep-look-to-the-cql-where-clause