ArcSDESQLExecute (arcpy)
Resumen
The ArcSDESQLExecute class provides a means of executing SQL statements via an ArcSDE connection.
Debate
Precaución:- Las tablas de ArcSDE y GDB no se deben modificar utilizando nada que no sea el software de ArcGIS. Se pueden producir daños si estas tablas del sistema se editan directamente utilizando SQL.
- Las ediciones con SQL de datos sometidos al control de versiones solo se deben hacer a través de vistas versionadas.
- Para las geodatabases implementadas en un sistema de administración de bases de datos relacionales (DBMS) utilizando tipos de datos y formatos de tablas del DBMS, se puede utilizar el SQL del propio DBMS para trabajar con la información almacenada en la base de datos.
- Al acceder a la información en una geodatabase a través de SQL, las aplicaciones externas pueden acceder a los datos tabulares que administra la geodatabase. Estas aplicaciones externas pueden ser aplicaciones de bases de datos no espaciales o aplicaciones espaciales personalizadas desarrolladas en un entorno distinto de ArcObjects. Sea consciente, sin embargo, de que el acceso SQL a la geodatabase omite la funcionalidad de la geodatabase, tal como topología, redes, terrenos u otras extensiones de clase o espacio de trabajo.
- Podría ser posible usar las entidades del DBMS como desencadenadores y los procedimientos almacenados para mantener las relaciones entre las tablas que son necesarias para ciertas funcionalidades de geodatabase. Sin embargo, si se ejecutan comandos SQL contra la base de datos sin tener en cuenta esta funcionalidad, por ejemplo si se emiten instrucciones INSERT para agregar registros a una tabla, se evitará la funcionalidad de la geodatabase y, probablemente, se dañarán las relaciones entre los datos de la geodatabase.
- Antes de intentar obtener acceso a objetos de ArcSDE o GDB, o de modificarlos, lea toda la documentación de ArcSDE y de la geodatabase relativa a la utilización de SQL contra los objetos GDB o ArcSDE en el DBMS.
Sintaxis
ArcSDESQLExecute ({server}, {instance}, {database}, {user}, {password})
| Parámetro | Explicación | Tipo de datos |
server |
Name of the server on which the database is installed or a valid connection file. | String |
instance |
The port number. | String |
database |
Name of the database. | String |
user |
The user name. | String |
password |
The password for the user name. | String |
Propiedades
| Propiedad | Explicación | Tipo de datos |
| transactionAutoCommit (Lectura y escritura) |
The autocommit interval. This can be used to force intermediate commits after a specified number of features have been modified. | Integer |
Descripción general de los métodos
| Método | Explicación |
| commitTransaction () |
No DML statements will be committed until the CommitTransaction method is called.  Nota:A commit may also occur when the connection to ArcSDE it terminated (check specific DBMS documentation to see how each DBMS deals with a disconnect while in a transaction). |
| execute (sql_statement) |
Sends the SQL statement to the database via an ArcSDE connection. If execute is run outside of a transaction, a commit will automatically take place once the SQL DML (INSERT, UPDATE, DELETE . . .) statement has been executed. |
| rollbackTransaction () |
Rollback any DML operations to the previous commit. |
| startTransaction () |
To control when your changes are committed to the database, call the startTransaction method before calling execute. This starts a transaction and no DML statements will be committed until the commitTransaction method is called. |
Métodos
commitTransaction ()
execute (sql_statement)
| Parámetro | Explicación | Tipo de datos |
sql_statement |
The SQL statement. The execute method returns a list of lists in the case where the statement returns rows from a table; for statements that do not return rows, it will return an indication of the success or failure of the statement (True for success; None for failure). Statements that return a single value from a single row will return the value in an appropriate type (string, float, float). | Variant |
rollbackTransaction ()
startTransaction ()
Ejemplo de código
Query for the number of each crime type and return a list of lists of the crime type and count of incidents.
import arcpy
# Use an sde connection file to create the connection
sde = r'Database Connections\Connection to bedrock.sde'
sde_conn = arcpy.ArcSDESQLExecute(sde)
table_name = 'vtest.GDB.Crime'
field_name = 'CRIMETYPE'
sql = '''
SELECT {0}, COUNT({0}) AS f_count FROM {1}
GROUP BY {0}
ORDER BY f_count DESC
'''.format(field_name, table_name)
sde_return = sde_conn.execute(sql)
for i in sde_return:
print('{}: {}'.format(*i))
Ejecutar una lista de instrucciones SQL
import sys
import arcpy
try:
# Make data path relative
arcpy.env.workspace = sys.path[0]
# Two ways to create the object, which also creates the
# connection to ArcSDE.
# Using the first method, pass a set of strings containing
# the connection properties:
# <serverName>, <portNumber>, <version>, <userName>, <password>
# arcpy.ArcSDESQLExecute("gpserver3","5151","#","toolbox","toolbox")
# Using the second method pass the path to a valid ArcSDE connection file
sde_conn = arcpy.ArcSDESQLExecute(r"data\Connection to GPSERVER3.sde")
# Get the SQL statements, separated by ; from a text string.
sql_statement = arcpy.GetParameterAsText(0)
sql_statement_list = sql_statement.split(";")
print("+++++++++++++++++++++++++++++++++++++++++++++\n")
# For each SQL statement passed in, execute it.
for sql in sql_statement_list:
print("Execute SQL Statement: {0}".format(sql))
try:
# Pass the SQL statement to the database.
sde_return = sde_conn.execute(sql)
except Exception as err:
print(err)
sde_return = False
# If the return value is a list (a list of lists), display
# each list as a row from the table being queried.
if isinstance(sde_return, list):
print("Number of rows returned by query: {0} rows".format(
len(sde_return)))
for row in sde_return:
print(row)
print("+++++++++++++++++++++++++++++++++++++++++++++\n")
else:
# If the return value was not a list, the statement was
# most likely a DDL statement. Check its status.
if sde_return == True:
print("SQL statement: {0} ran successfully.".format(sql))
else:
print("SQL statement: {0} FAILED.".format(sql))
print("+++++++++++++++++++++++++++++++++++++++++++++\n")
except Exception as err:
print(err)
Actualización condicional utilizando una transacción
# WARNING - DO NOT USE ON VERSIONED TABLES OR FEATURE CLASSES.
# DO NOT USE ON ANY ArcSDE or GDB SYSTEM TABLES.
# DOING SO MAY RESULT IN DATA CORRUPTION.
import sys
import arcpy
try:
# Make data path relative (not relevant unless data is moved
# here and paths modified)
arcpy.env.workspace = sys.path[0]
# Column name:value that should be in the record.
sql_values = {"STREET_NAM": "'EUREKA'"}
# Value that is incorrect if found in the above column.
bad_val = "'EREKA'"
#List of tables to look in for the bad value.
tables = ["streetaddresses_blkA", "streetaddresses_blkB",
"streetaddresses_blkC"]
# Two ways to create the object, which also creates the connection
# to ArcSDE.
# Using the first method, pass a set of strings containing the
# connection properties:
# <serverName>, <portNumber>, <version>, <userName>, <password>
sde_conn = arcpy.ArcSDESQLExecute("gpserver3", "5151", "#",
"toolbox", "toolbox")
# Using the second method pass the path to a valid ArcSDE connection file
# arcpy.ArcSDESQLExecute("data\Connection to GPSERVER3.sde")
for tbl in tables:
print("+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++")
for col, val in sql_values.items():
print("+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++")
# Check for the incorrect value in the column for the
# specific rows. If the table contains the incorrect value,
# correct it using the update SQL statement.
print("Analyzing table {0} for bad data: "
"Column:{1} Value: {2}".format(tbl, col, bad_val))
try:
sql = "select OBJECTID,{0} from {1} where {0} = {2}".format(
col, tbl, bad_val)
print("Attempt to execute SQL Statement: {0}".format(sql))
sde_return = sde_conn.execute(sql)
except Exception as err:
print(err)
sde_return = False
if isinstance(sde_return, list):
if len(sde_return) > 0:
print("Identified {0} rows with incorrect data. Starting "
"transaction for update.".format(len(sde_return)))
# Start the transaction
sde_conn.startTransaction()
print("Transaction started...")
# Perform the update
try:
sql = "update {0} set {1}={2} where {1} = {3}".format(
tbl, col, val, bad_val)
print("Changing bad value: {0} to the good value: "
"{1} using update statement:\n {2}".format(
bad_val, val, sql))
sde_return = sde_conn.execute(sql)
except Exception as err:
print(err)
sde_return = False
# If the update completed successfully, commit the
# changes. If not, rollback.
if sde_return == True:
print("Update statement: \n"
"{0} ran successfully.".format(sql))
# Commit the changes
sde_conn.commitTransaction()
print("Committed Transaction")
# List the changes.
try:
print("Displaying updated rows for "
"visual inspection.")
sql = "select OBJECTID" + \
",{0} from {1} where {0} = {2}".format(
col, tbl, val)
print("Executing SQL Statement: \n{0}".format(sql))
sde_return = sde_conn.execute(sql)
except Exception as err:
print(err)
sde_return = False
if isinstance(sde_return, list):
print("{0} rows".format(len(sde_return)))
for row in sde_return:
print(row)
print("++++++++++++++++++++++++++++++++++++++++\n")
else:
if sde_return == True:
print("SQL statement: \n{0}\n"
"ran successfully.".format(sql))
else:
print("SQL statement: \n{0}\n"
"FAILED.".format(sql))
print("++++++++++++++++++++++++++++++++++++++++\n")
print("++++++++++++++++++++++++++++++++++++++++\n")
else:
print("SQL statement: \n{0}\nFAILED. "
"Rolling back all changes.".format(sql))
# Rollback changes
sde_conn.rollbackTransaction()
print("Rolled back any changes.")
print("++++++++++++++++++++++++++++++++++++++++\n")
else:
print "No records required updating."
# Disconnect and exit
del sde_conn
print("+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++")
except Exception as err:
print(err)
Temas relacionados
4/26/2014