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| 1 | +## Deleting data from the DB |
| 2 | + |
| 3 | +There are three ways to delete data from a DB |
| 4 | + |
| 5 | +- delete_by_query |
| 6 | +- delete_by_hash_id |
| 7 | +- purge |
| 8 | + |
| 9 | +### delete_by_query |
| 10 | + |
| 11 | +The `delete_by_query` accepts a single condition which removes all the rows that mathes that condition |
| 12 | + |
| 13 | +```python |
| 14 | +from onstrodb import OnstroDb |
| 15 | + |
| 16 | +schema = { |
| 17 | + "name": {"type": "str", "required": True}, |
| 18 | + "age": {"type": "int"} |
| 19 | +} |
| 20 | + |
| 21 | +db = OnstroDb(db_name="test", schema=schema) |
| 22 | + |
| 23 | +db.add([ |
| 24 | + {"name": "ad", "age": 3}, |
| 25 | + {"name": "fred", "age": 4}, |
| 26 | + {"name": "dev", "age": 5} |
| 27 | +]) |
| 28 | + |
| 29 | +print(db) |
| 30 | + |
| 31 | +db.delete_by_query({"name": "ad"}) # queries can only be one condition long(There is a work around for this) |
| 32 | + |
| 33 | +print(db) |
| 34 | +``` |
| 35 | + |
| 36 | + { '7b672af4': {'name': 'ad', 'age': 3}, |
| 37 | + '93b626d2': {'name': 'fred', 'age': 4}, |
| 38 | + '41907268': {'name': 'dev', 'age': 5}} |
| 39 | + {'93b626d2': {'name': 'fred', 'age': 4}, '41907268': {'name': 'dev', 'age': 5}} |
| 40 | + |
| 41 | +### delete_by_hash_id |
| 42 | + |
| 43 | +The `delete_by_hash_id` taskes the hash id of the row as an argument |
| 44 | + |
| 45 | +```python |
| 46 | +from onstrodb import OnstroDb |
| 47 | + |
| 48 | +schema = { |
| 49 | + "name": {"type": "str", "required": True}, |
| 50 | + "age": {"type": "int"} |
| 51 | +} |
| 52 | + |
| 53 | +db = OnstroDb(db_name="test", schema=schema) |
| 54 | + |
| 55 | +db.add([ |
| 56 | + {"name": "ad", "age": 3}, |
| 57 | + {"name": "fred", "age": 4}, |
| 58 | + {"name": "dev", "age": 5} |
| 59 | +]) |
| 60 | + |
| 61 | +print(db) |
| 62 | + |
| 63 | +db.delete_by_hash_id("93b626d2") |
| 64 | + |
| 65 | +print(db) |
| 66 | +``` |
| 67 | + |
| 68 | + { '7b672af4': {'name': 'ad', 'age': 3}, |
| 69 | + '93b626d2': {'name': 'fred', 'age': 4}, |
| 70 | + '41907268': {'name': 'dev', 'age': 5}} |
| 71 | + {'7b672af4': {'name': 'ad', 'age': 3}, '41907268': {'name': 'dev', 'age': 5}} |
| 72 | + |
| 73 | +### purge |
| 74 | + |
| 75 | +Purging a DB will delete all the rows. |
| 76 | + |
| 77 | +```python |
| 78 | +from onstrodb import OnstroDb |
| 79 | + |
| 80 | +schema = { |
| 81 | + "name": {"type": "str", "required": True}, |
| 82 | + "age": {"type": "int"} |
| 83 | +} |
| 84 | + |
| 85 | +db = OnstroDb(db_name="test", schema=schema) |
| 86 | + |
| 87 | +db.add([ |
| 88 | + {"name": "ad", "age": 3}, |
| 89 | + {"name": "fred", "age": 4}, |
| 90 | + {"name": "dev", "age": 5} |
| 91 | +]) |
| 92 | + |
| 93 | +print(db) |
| 94 | + |
| 95 | +db.purge() |
| 96 | +db.commit() # to save the changes |
| 97 | + |
| 98 | +print(db) |
| 99 | +``` |
| 100 | + |
| 101 | + { '7b672af4': {'name': 'ad', 'age': 3}, |
| 102 | + '93b626d2': {'name': 'fred', 'age': 4}, |
| 103 | + '41907268': {'name': 'dev', 'age': 5}} |
| 104 | + |
| 105 | + {} |
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