Hello I am trying to execute the following Oracle Query. I confirmed i can successfully connect to the database using cx_Oracle but my query is not executing. This is a large table and i am trying to limit the number of rows to 10
query1 = """
select *
from
(select *
from some_table
)
where rownum < 10;
"""
df_ora1 = pd.read_sql(query1, con=connection1)
I am getting the following error but cant figure out what the invalid character is!
DatabaseError: ORA-00911: invalid character
Please help!
Remove the semi-colon from the SQL statement. Semi-colons are not part of SQL.
query1 = """ select * from (select * from some_table ) where rownum < 10 """
Related
Hi all I'm new to Dask.
I faced an error when I tried using read_sql_query to get data from Oracle database.
Here is my python script:
con_str = "oracle+cx_oracle://{UserID}:{Password}#{Domain}/?service_name={Servicename}"
sql= "
column_a, column_b
from
database.tablename
where
mydatetime >= to_date('1997-01-01 00:00:00','YYYY-MM-DD HH24:MI:SS')
"
from sqlalchemy.sql import select, text
from dask.dataframe import read_sql_query
sa_query= select(text(sql))
ddf = read_sql_query(sql=sa_query, con=con, index_col="index", head_rows=5)
I refered this post: Reading an SQL query into a Dask DataFrame
Remove "select" string from my query.
And I got an cx_Oracle.DatabaseError with missing expression [SQL: SELECT FROM DUAL WHERE ROWNUM <= 5]
But I don't get it where the query came from.
Seem like it didn't execute the sql code I provided.
I'm not sure which part I did not config right.
*Note: using pandas.read_sql is ok , only fail when using dask.dataframe.read_sql_query
I have the following SQL statement where i am reading the database to get the records for 1 day. Here is what i tried in pgAdmin console -
SELECT * FROM public.orders WHERE createdat >= now()::date AND type='t_order'
I want to convert this to the syntax of psycopg2but somehow it throws me errors -
Database connection failed due to invalid input syntax for type timestamp: "now()::date"
Here is what i am doing -
query = f"SELECT * FROM {table} WHERE (createdat>=%s AND type=%s)"
cur.execute(query, ("now()::date", "t_order"))
records = cur.fetchall()
Any help is deeply appreciated.
DO NOT use f strings. Use proper Parameter Passing
now()::date is better expressed as current_date. See Current Date/Time.
You want:
query = "SELECT * FROM public.orders WHERE (createdat>=current_date AND type=%s)"
cur.execute(query, ["t_order"])
If you want dynamic identifiers, table/column names then:
from psycopg2 import sql
query = sql.SQL("SELECT * FROM {} WHERE (createdat>=current_date AND type=%s)").format(sql.Identifier(table))
cur.execute(query, ["t_order"])
For more information see sql.
I have following SparkSQL (Spark pool - Spark 3.0) code and I want to pass a variable to it. How can I do that? I tried the following:
#cel 1 (Toggle parameter cell):
%%pyspark
stat = 'A'
#cel2:
select * from silver.employee_dim where Status= '$stat'
When you're running your cell as PySpark, you can pass a variable to your query like this:
#cel 1 (Toggle parameter cell):
%%pyspark
stat = 'A' #define variable
#cel2:
%%pyspark
query = "select * from silver.employee_dim where Status='" + stat + "'"
spark.sql(query) #execute SQL
Since you're executing a SELECT statement, I assume you might want to load the result to a DataFrame:
sqlDf = spark.sql(query)
sqlDf.head(5) #select first 5 rows
Why following code is giving syntax error "sqlite3.OperationalError: near "?": syntax error"
import sqlite3
connection = sqlite3.connect('data.db')
cursor = connection.cursor()
table = "device_store"
uuid = "bbebe39e-fe2e-4817-b022-a3ef13bd6283"
page = 1
POSTS_PER_PAGE = 10
query = "SELECT * FROM ? WHERE uuid=? LIMIT ? OFFSET ?"
result = cursor.execute(query, (table, uuid, POSTS_PER_PAGE, 0))
rows = result.fetchall()
connection.close()
print("==>> Printing rows <<==")
print(rows)
The error is caused by the placeholder in FROM ?, not the others. Table names can't be passed as parameters, they have to be hardcoded in the statement.
I am trying to use cx_Oracle to query a table in oracle DB (version 11.2) and get rows with values in a column between a datetime range.
I have tried the following approaches:
Tried between clause as described here, but cursor gets 0 rows
parameters = (startDateTime, endDateTime)
query = "select * from employee where joining_date between :1 and :2"
cur = con.cursor()
cur.execute(query, parameters)
Tried the TO_DATE() function and Date'' qualifiers. Still no result for Between or >= operator. Noteworthy is that < operator works. I also got the same query and tried in a sql client, and the query returns results. Code:
#returns no rows:
query = "select * from employee where joining_date >= TO_DATE('" + startDateTime.strftime("%Y-%m-%d") + "','yyyy-mm-dd')"
cur = con.cursor()
cur.execute(query)
#tried following just to ensure that some query runs fine, it returns results:
query = query.replace(">=", "<")
cur.execute(query)
Any pointers about why the between and >= operators are failing for me? (my second approach was in line with the answer in Oracle date comparison in where clause but still doesn't work for me)
I am using python 3.4.3 and used cx_Oracle 5.3 and 5.2 with oracle client 11g on windows 7 machine
Assume that your employee table contains the field emp_id and the row with emp_id=1234567 should be retrieved by your query.
Make two copies of your a program that execute the following queries
query = "select to_char(:1,'YYYY-MM-DD HH24:MI:SS')||' >= '||to_char(joining_date,'YYYY-MM-DD HH24:MI:SS')||' >= '||to_char(:2,'YYYY-MM-DD HH24:MI:SS') resultstring from employee where emp_id=1234567"
and
query="select to_char(joining_date,'YYYY-MM-DD HH24:MI:SS')||' >= '||to_char(TO_DATE('" + startDateTime.strftime("%Y-%m-%d") + "','yyyy-mm-dd'),'YYYY-MM-DD HH24:MI:SS') resultstring from employee where emp_id=1234567"
Show us the code and the value of the column resultstring
You are constructing SQL queries as strings when you should be using parameterized queries. You can't use parameterization to substitute the comparison operators, but you should use it for the dates.
Also, note that the referenced answer uses the PostgreSQL parameterisation format, whereas Oracle requires you to use the ":name" format.