SQL Server 2019

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CREATE TABLE project(
   SRC_START_DTTM VARCHAR(24) NOT NULL
  ,Concept_ID_DFF BIGINT
);
INSERT INTO project(SRC_START_DTTM,Concept_ID_DFF) VALUES ('2021-09-20 18:53:56.003',NULL);
1 rows affected

INSERT INTO project(SRC_START_DTTM,Concept_ID_DFF) VALUES ('2021-09-20 18:54:22.150',300000005876166);
1 rows affected

INSERT INTO project(SRC_START_DTTM,Concept_ID_DFF) VALUES ('2021-09-23 14:02:49.000',300000005876166);
1 rows affected

CREATE TABLE proposal(
   SRC_START_DTTM VARCHAR(24) NOT NULL
  ,Concept_ID_DFF BIGINT
);
INSERT INTO proposal(SRC_START_DTTM,Concept_ID_DFF) VALUES ('1262450.00',300000005876166);
INSERT INTO proposal(SRC_START_DTTM,Concept_ID_DFF) VALUES ('1510546.00',300000005876166);
INSERT INTO proposal(SRC_START_DTTM,Concept_ID_DFF) VALUES ('12874.00',300000005876166);
3 rows affected

select *
from project p
cross join proposal l


SRC_START_DTTM
Concept_ID_DFF
SRC_START_DTTM
Concept_ID_DFF


2021-09-20 18:53:56.003
null
1262450.00
300000005876166

2021-09-20 18:54:22.150
300000005876166
1262450.00
300000005876166

2021-09-23 14:02:49.000
300000005876166
1262450.00
300000005876166

2021-09-20 18:53:56.003
null
1510546.00
300000005876166

2021-09-20 18:54:22.150
300000005876166
1510546.00
300000005876166

2021-09-23 14:02:49.000
300000005876166
1510546.00
300000005876166

2021-09-20 18:53:56.003
null
12874.00
300000005876166

2021-09-20 18:54:22.150
300000005876166
12874.00
300000005876166

2021-09-23 14:02:49.000
300000005876166
12874.00
300000005876166

SRC_START_DTTM	Concept_ID_DFF	SRC_START_DTTM	Concept_ID_DFF
2021-09-20 18:53:56.003	null	1262450.00	300000005876166
2021-09-20 18:54:22.150	300000005876166	1262450.00	300000005876166
2021-09-23 14:02:49.000	300000005876166	1262450.00	300000005876166
2021-09-20 18:53:56.003	null	1510546.00	300000005876166
2021-09-20 18:54:22.150	300000005876166	1510546.00	300000005876166
2021-09-23 14:02:49.000	300000005876166	1510546.00	300000005876166
2021-09-20 18:53:56.003	null	12874.00	300000005876166
2021-09-20 18:54:22.150	300000005876166	12874.00	300000005876166
2021-09-23 14:02:49.000	300000005876166	12874.00	300000005876166